Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
Science Grade 07 Unit 09 Exemplar Lesson 01: Physical, Chemical, and Energy Changes in Digestion
This lesson is one approach to teaching the State Standards associated with this unit. Districts are encouraged to customize this lesson by
supplementing with district-approved resources, materials, and activities to best meet the needs of learners. The duration for this lesson is only a
recommendation, and districts may modify the time frame to meet students’ needs. To better understand how your district may be implementing
CSCOPE lessons, please contact your child’s teacher. (For your convenience, please find linked the TEA Commissioner’s List of State Board of
Education Approved Instructional Resources and Midcycle State Adopted Instructional Materials.)
Lesson Synopsis
In this lesson, students will study the chemical and physical changes of matter. The lesson will guide students to identify some common elements in
organic compounds, distinguish between chemical and physical changes in matter during digestion, and recognize that large molecules can be broken
down into smaller molecules. Students will also illustrate how chemical energy is transferred to heat and thermal energy during digestion.
TEKS
The Texas Essential Knowledge and Skills (TEKS) listed below are the standards adopted by the State Board of Education, which are required by Texas
law. Any standard that has a strike-through (e.g. sample phrase) indicates that portion of the standard is taught in a previous or subsequent unit. The
TEKS are available on the Texas Education Agency website at http://www.tea.state.tx.us/index2.aspx?id=6148.
7.6
Matter and energy. The student knows that matter has physical and chemical properties and can undergo physical and
chemical changes. The student is expected to:
7.6A Identify that organic compounds contain carbon and other elements such as hydrogen, oxygen, phosphorus,
nitrogen, or sulfur.
Supporting Standard
7.6B Distinguish between physical and chemical changes in matter in the digestive system.
Supporting Standard
7.6C Recognize how large molecules are broken down into smaller molecules such as carbohydrates can be broken
down into sugars.
7.7
Force, motion, and energy. The student knows that there is a relationship among force, motion, and energy. The student
is expected to:
7.7B Illustrate the transformation of energy within an organism such as the transfer from chemical energy to heat and
thermal energy in digestion.
Scientific Process TEKS
7.1
Scientific investigation and reasoning. The student, for at least 40% of the instructional time, conducts laboratory and
field investigations following safety procedures and environmentally appropriate and ethical practices. The student is
expected to:
7.1A Demonstrate safe practices during laboratory and field investigations as outlined in the Texas Safety Standards.
7.2
Scientific investigation and reasoning. The student uses scientific inquiry methods during laboratory and field
investigations. The student is expected to:
7.2C Collect and record data using the International System of Units (SI) and qualitative means such as labeled
drawings, writing, and graphic organizers.
7.3
Scientific investigation and reasoning. The student uses critical thinking, scientific reasoning, and problem solving to
make informed decisions and knows the contributions of relevant scientists. The student is expected to:
7.3B Use models to represent aspects of the natural world such as human body systems and plant and animal cells.
7.3C Identify advantages and limitations of models such as size, scale, properties, and materials.
7.4
Scientific investigation and reasoning. The student knows how to use a variety of tools and safety equipment to conduct
science inquiry. The student is expected to:
7.4A Use appropriate tools to collect, record, and analyze information, including life science models, hand lens, stereoscopes, microscopes,
beakers, Petri dishes, microscope slides, graduated cylinders, test tubes, meter sticks, metric rulers, metric tape measures, timing devices,
hot plates, balances, thermometers, calculators, water test kits, computers, temperature and pH probes, collecting nets, insect traps, globes,
digital cameras, journals/notebooks, and other equipment as needed to teach the curriculum.
7.4B Use preventative safety equipment, including chemical splash goggles, aprons, and gloves, and be prepared to use emergency safety
equipment, including an eye/face wash, a fire blanket, and a fire extinguisher.
GETTING READY FOR INSTRUCTION
Last Updated 05/28/13
page 1 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
Performance Indicators
Grade 07 Science Unit 09 PI 01
Create a model of a sugar molecule. Draw a five-pane comic strip to describe how it began as a carbohydrate and how it was broken down both chemically and physically
during digestion into a sugar molecule. Include the energy transformations taking place throughout the process.
Standard(s): 7.3B , 7.6A , 7.6B , 7.6C , 7.7B
ELPS ELPS.c.1E , ELPS.c.5F
Key Understandings
Physical changes deal with energy and states of matter, while chemical changes result in new substances with new properties. These changes
occur at the molecular level.
— How do chemical and physical changes in digestion differ?
— How are large molecules, such as carbohydrates, broken down into smaller molecules of sugar?
— How can it be determined that a compound is organic?
Digestion of matter entails both physical and chemical changes.
— How is energy transformed during digestion?
Vocabulary of Instruction
thermal energy
molecule
organic compound
element
chemical change
digestion
carbohydrates
physical change
cellular respiration
compound
Materials
baking soda (5 cc or 1 tsp., for demonstration, per class)
beakers (250 mL and 500 mL)
chalk (1 piece per group)
container (large enough to hold items listed, 1 per group)
copper wire or pipe (1 per group)
foil
gelatin (flavored, 1 box per group)
gloves (2 pairs per group)
grocery bag (disposable plastic, 1 piece per group)
hot plate (for demonstration, 1 per teacher)
hydrogen peroxide ( 75 mL per group, per class)
ice cube (for demonstration, multiple per teacher)
iron nail (1 per group)
lighter (long, for demonstration, 1 per teacher)
marshmallows (miniature, colored, 1 bag per group)
marshmallows (miniature, white, 1 bag per class)
MSDS for hydrogen peroxide (see Advance Preparation, 1 per group)
paper
paper towel (1 per student)
Periodic Table of the Elements (see Advance Preparation,1 per student, may have been previously distributed and affixed to the notebook)
permanent marker (1 per teacher)
Petri dish (1 per group)
raw chicken or beef liver (1 piece about thumb nail size per group, per class)
safety goggles (1 pair per student)
scissors (1 per group)
soda cracker (2 per student)
stick margarine (1 pat per group)
sugar (1 Tbsp. per group)
sugar cubes (for demonstration, 1 per class)
table salt (1 Tbsp. or 15 cc per group)
thermometer or temperature probe (1 per group)
timing device (1 per group)
tongs (for demonstration, 1 per teacher)
toothpicks (round, 24 per group)
vinegar (for demonstration, 50 mL per class)
water (per class)
Attachments
All attachments associated with this lesson are referenced in the body of the lesson. Due to considerations for grading or student assessment,
Last Updated 05/28/13
page 2 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
attachments that are connected with Performance Indicators or serve as answer keys are available in the district site and are not accessible on the
public website.
Teacher Resource: Element Comparison (1 for projection)
Teacher Resource: Building Organic Compounds (1 for projection)
Teacher Resource: Organic Compound Clipart (see Advance Preparation,1 set per group)
Teacher Resource: Transformation of Energy during Digestion (1 for projection and per group)
Teacher Resource: Transformation of Energy during Digestion KEY
Teacher Resource: Glucose Model (see Advance Preparation,1 per pair or group)
Teacher Resource: Performance Indicator Instruction KEY (1 for projection)
Resources
None Identified
Advance Preparation
1. Collect, assemble, and prepare all materials.
2. Prior to Day 1:
Ensure that each student has a copy of the Periodic Table of the Elements. If not, you will need to print the periodic table from the Grade 8
STAAR Resources. See the TEA link listed in Resources and References section.
Prepare a table set of materials for each group to use in the Explore/Explain: Element, Compound, or Organic Compound. These items may be
placed on a tray or in a shoebox for distribution and easy clean up. All materials are one per group or as indicated.
Cut a plastic, disposable, grocery bag into smaller squares.
Include an object made of iron such as an iron nail or a cast iron pan.
Strip the insulation off an old electrical cord to expose the copper wire. Cut it into small sections.
Place about one tablespoon of salt in one half of a Petri dish and one tablespoon of sugar in the other half.
Cut a stick of margarine into pats, and place one pat per group on a small piece of foil.
A piece of chalk and an unopened box of flavored gelatin will complete the box of samples.
Use a permanent marker to write identification labels for the sugar and salt, and place in them in the Petri dishes.
Print on cardstock, laminate, and cut out the Teacher Resource: Organic Compounds Clipart. Each group will need one DNA card and
one insulin injection card. There are five sets on the resource page. Make enough copies so that each group has one set of images.
3. Prior to Day 3:
Pre-cut liver pieces (about the size of a thumbnail) for each group.
Print on cardstock and laminate an MSDS for hydrogen peroxide for each group. See the Resources and References section.
Print on cardstock, and laminate the Teacher Resource: Transformation of Energy during Digestion (1 per group).
4. Prior to Day 4: Print on cardstock, and laminate the Teacher Resource: Glucose Model (1 per student).
5. Prepare attachment(s) as necessary.
Background Information
This lesson bundles student expectations that address chemical and physical changes in matter and the transformation of energy in the digestive system. Grade 7 science is
interdisciplinary in nature; however, much of the content focus is on organisms and the environment. The Chemistry components of Grade 7 will be addressed through a Life
Science connection, in this case digestion.
In previous grades, students became familiar with physical properties of matter and energy transformations. Chemical changes happen on a molecular level and change the
substance into a new one with different properties. Physical changes deal with energy and states of matter; they generally involve a change in the size, shape, or state of matter
of the substance. Prior to this lesson, students looked at the connection between structure and function on the cellular level, organ and system levels, and internal adaptations.
During the previous unit, students studied the human body systems. During this lesson, students will identify organic compounds and the elements involved and recognize
how large molecules are broken down into smaller ones. The elements and compounds identified in this unit were chosen because they appear frequently throughout the
content of Grades 6 through 8. They are common to Life, Earth, and Physical Science.
Atoms are studied in Grade 8 TEKS. In Grade 7, basic information will need to be presented on molecules. Bonding in atoms and molecules is not covered until chemistry.
Students will have to accept the fact that bonding is involved in the formation of molecules. Bonds are not physical objects but relate to forces that hold atoms and molecules
together. Bonds are broken and reformed as substances undergo chemical changes. Elements and compounds were covered in Grade 6, but students may need some
information or review on the following basics.
— Atoms are the smallest particles from which elements are made.
— Molecules are two or more atoms bonded together to form a substance that exists on its own and keeps it properties.
— Compounds contain atoms from two or more elements chemically bonded to form a new and different substance.
— Organic compounds are made up of carbon atoms bonded to atoms of other elements.
Thermal energy is a form of energy. The process of the movement of thermal energy produces heat. Digestion involves physical and chemical changes. During chemical
changes, food is broken down and releases thermal energy. The movement of the thermal energy through the body is heat.
STAAR Note:
Last Updated 05/28/13
page 3 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
Student expectation 7.7B reinforces content regarding energy transformations that students covered in Supporting Standard 6.9C, which will be assessed on the STAAR Grade
8 Science Assessment. Student Expectations 7.6A and 7.6B, dealing with organic compounds and changes involved in digestion, are both Supporting Standards that will be
assessed in Grade 8. In addition, 7.6B builds content for Readiness Standard 8.5E, which deals with the evidence of a chemical reaction.
INSTRUCTIONAL PROCEDURES
Instructional Procedures
Notes for Teacher
ENGAGE – Element Comparisons
NOTE: 1 Day = 50 minutes
Suggested Day 1
1. Instruct students to take out a sheet of paper and make two columns. Label one
column “Human Body” and the other column “Earth’s Crust.” Number each column
from 1–5.
2. Distribute a periodic table to each student, or if previously distributed, instruct
students to reference it.
Say:
Look at your periodic table, and write down the five elements that you
think are the most common in each column. You have five minutes.
3. After students have made their lists, allow them to share what they thought the top five
elements are. Create a class list on the board.
4. Project the Teacher Resource: Element Comparison.
Ask:
Look at the list. How close to the actual answer did the class list on the
board get? (Answers will vary.)
Why do you think the elements most common in the human body are not
the same as the ones in the Earth’s crust? (Answers will vary, but lead
students to the conclusion that living things and non-living things have different
makeup and needs.)
Materials:
Periodic Table of the Elements (see Advance
Preparation,1 per student, may have been
previously distributed and affixed to the notebook)
paper (notebook, 1 per student)
Attachments:
Teacher Resource: Element Comparison (1 for
projection)
Instructional Notes:
The six elements designated with the checkmark (√) will be used
again in the discussion of organic compounds. The elements and
compounds identified were chosen because they appear frequently
throughout the content of Grades 6–8. They are common elements
in Life, Earth, and Physical Science.
In Grade 6, students studied elements in living things, the Earth, the
5. Ask:
atmosphere, and the oceans.
What are the rules for writing chemical symbols? Elements are represented
by 1–3 letters. The first letter is always capitalized. The following letters are always
lower case. The letters are always printed.
Science Notebooks:
Students record the rules for writing chemical symbols in their
notebooks, and list the six elements (√) found in the human body.
6. Instruct students to work in pairs to create the rules for writing chemical symbols.
Instruct them to record the rules in their notebooks.
7. Ask students to share their rules, and require them to support their rules with
examples/evidence. Allow students to revise their chemical symbol notes based upon
discussion.
8. Project the following rules, and allow students to revise their notes in their notebooks.
The first letter in a symbol always begins with a capital letter.
If the symbol is composed of two or three letters, the second and third letters are
written in lower case.
Letters are always printed, not written in cursive.
9. Project the Teacher Resource: Element Comparison again. Instruct students to
write both the name and chemical symbol for the six elements with a checkmark (√)
beside them in their science notebooks. Inform students that these are the ones they
will need to remember. A device for remembering these elements is the word
“SPONCH”. These elements are found in all living things.
EXPLORE/EXPLAIN – Element, Compound, or Organic Compound
Suggested Days 1 (continued) and 2
1. Instruct students to reference their periodic table. Ask students to brainstorm what an
element is with a partner. Ask a few students to share some explanations.
2. Ask:
What is an element? An element is a pure substance that cannot be broken
down into simpler substances. It contains only one type of atom.
Instruct students to record the term and definition in their notebooks.
Last Updated 05/28/13
Materials:
Periodic Table of the Elements (1 per student,
previously distributed)
permanent marker (1 per teacher)
Petri dish (1 per group)
iron nail (1 per group)
page 4 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
3. Point out that the use of symbols on the periodic table is to represent elements that
make up all matter. Instruct students to locate the six elements (with the √) they
recorded in their notebook.
4. Hold up a piece of copper wire, and ask students what element it is made from (Cu).
Ask students to find the item in their table box. Instruct the students to find copper
(Cu) on their periodic tables. Show students something made of iron (nail), and ask
them what element it is made from (Fe). Ask students to find the item in their table
box. Instruct students to find iron (Fe) on the periodic table.
copper wire or pipe (1 per group)
table salt (1 Tbsp. or 15 cc per group)
chalk (1 piece per group)
sugar (1 Tbsp. per group)
stick margarine (1 pat per group)
gelatin (flavored, 1 box per group)
grocery bag (disposable plastic, 1 piece per group)
foil (1 piece per group)
container (large enough to hold items listed, 1 per
group)
5. Show the students some table salt (NaCl), and ask what element is made from. Ask
students to find the item in their table box. Instruct students to locate “sodium chloride”
on the periodic table. The students should tell you that they cannot find it, but they
Attachments:
can find sodium and chlorine. Repeat with a sample of chalk known as calcium
Teacher Resource: Element Comparison (1 for
carbonate (CaCO3). The students should be able to identify calcium, carbon, and
projection, from previous activity)
oxygen but not find the compound listed.
Teacher Resource: Building Organic
6. Ask:
Compounds (1 for projection)
Teacher Resource: Organic Compound Clipart
Why isn’t sodium chloride listed on the periodic table? It’s a compound. Only
(see Advance Preparation, 1 set per group)
elements are listed on the table.
What is a compound? A compound is a substance made by chemically
combining two or more elements to form a new and different substance, and the
Instructional Notes:
bond cannot be broken by physical means.
In Grade 6, students learned the common elements in living things
Is O2 a compound? No, because it is made up of only one element. It is
and the Earth’s crust.
considered a molecule because it is two atoms of the same element. A molecule
isi formed when any two or more atoms join.
Explain to students that all compounds are considered molecules because a
molecule is when any two atoms join. However, all molecules are not considered
compounds. There must be two or more different elements present to be
considered a compound.
Instruct students to record the terms and definitions in their notebooks.
7. Point out that there are some very common elements that compose important
compounds that, in turn, make up the Earth and organisms on it. Reference the
Teacher Resource: Element Comparison. Also, point out that photosynthesis and
cellular respiration could not occur without some of these compounds and elements.
8. Post or project and review the equation for photosynthesis:
Students used the periodic table in Grade 6 to look at placement of
metals, non-metals, and metalloids.
The formulas for photosynthesis and the element names were
addressed in previous units of study. Students should be able to
identify the elements in cellular respiration as well.
Misconception:
Students may think molecules have the same
properties as the atoms from which they are
composed.
Ask:
Which of the substances in the photosynthesis equation are elements?
(None. They are all compounds or molecules made up of elements.)
Which of the substances in the photosynthesis equation are compounds?
(CO2, H2O, C6H1206)
Which of the substances are molecules? (O2, CO2, H2O, C6H1206) Students
may find the inclusion of the compounds confusing. You may need to go back to
the definition of a molecule and explicitly show the connection.
Which elements compose glucose? (Carbon, hydrogen, and oxygen)
STAAR Notes:
Student expectation 7.7B reinforces content regarding energy
transformations that students covered in Supporting Standard 6.9C,
which will be assessed on the STAAR Grade 8 Science
Assessment. Student expectations 7.6A and 7.6B, dealing with
organic compounds and changes involved in digestion, are both
Supporting Standards that will be assessed in Grade 8. In addition,
7.6B builds content for Readiness Standard 8.5E, which deals with
the evidence of a chemical reaction.
9. Cellular respiration is the process that cells use to break sugars (glucose) into a form
that the cells can use for energy. This process occurs in plants and animals. Cellular
respiration takes food in the form of sugar or starch and uses it to create ATP (a
chemical the cell uses as energy). NOTE: The previous statement is background
information. Students are not responsible for knowing the details of cellular
respiration. Thermal energy also is produced in the process. Post or project the
chemical formula for cellular respiration:
Check For Understanding:
Students identify organic compounds based on elements listed in
formulas and justify their reasoning.
Science Notebooks:
Students record terms and definitions in their notebooks.
Ask:
Which of the substances in the cellular respiration equation are
elements? (None, they are all compounds or molecules.)
Which of the substances in the cellular respiration equation are
compounds? (CO2, H2O, C6H1206) NOTE: ATP is a compound, but students are
not expected to know this. Pointing this out could cause issues because students
might confuse the letters as symbols for elements. When they cannot locate an ‘A’
Last Updated 05/28/13
page 5 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
or a ‘T’ on the table, it will complicate things.
Which of the substances are molecules? (O2, H2O, C6H1206)
Which elements compose carbon dioxide? (Carbon and oxygen)
How are the two processes, photosynthesis and cellular respiration,
similar? Answers will vary. They both involve sugar, water, carbon dioxide, oxygen,
and energy. Photosynthesis uses energy to make sugar, and cellular respiration
uses sugar to produce energy.
10. Write the following definition of an organic compound on the board, and instruct the
students record it in their notebooks:
An organic compound is made up carbon atoms bonded to atoms of other
elements. Examples are carbohydrates, proteins, lipids, and nucleic acids.
11. Project the Teacher Resource: Building Organic Compounds. Lead students
through the handout. Explain to students that if one element is added to the chemical
makeup of a substance, the substance changes into a new and different substance.
12. Leave the projection of Teacher Resource: Building Organic Compounds
displayed. Hold up the piece of plastic bag. Ask students to use the Teacher
Resource: Building Organic Compounds to determine which elements make up the
plastic bag (H & O). Continue the process showing the sugar for carbohydrates and
the margarine for lipids (by adding O). Show the box of gelatin for protein (adding N)
and the card for insulin. Show the card for DNA (P). The Teacher Resource: Organic
Compound Clipart (see Advance Preparation) should be used for the insulin and
DNA cards.
13. Instruct students to reference the six elements in the human body they copied in their
notebooks earlier. (SPONCH)
14. Instruct students to work in pairs to compare the elements listed in their notebooks to
those listed on the Handout: Building Organic Compounds. Instruct students to
shade the box for each element on the periodic table. (SPONCH)
15. Instruct students to switch partners and share their comparisons with one another.
16. Facilitate a discussion based on the following questions.
Ask:
What do the six elements in the human body have in common with the
elements in organic compounds? (The elements are the same.)
Do you agree or disagree with the following statement?
Living things are made of organic compounds. (Agree; all living things contain
carbon combined with other elements.)
Why would some non-living things contain carbon? (They are made from
remains of once living organisms; for example, fossil fuels.)
17. Explain that carbon is the commonality for organic compounds. Project or post several
formulas for common compounds and ask the students to identify the ones that are
organic and to justify their answers. This is an opportunity for a formative assessment.
EXPLORE/EXPLAIN – Digestion Changes
Suggested Days 3 and 4
1. Review physical and chemical changes with students. Display the following scenarios,
and ask students to identify the scenarios as physical or chemical changes.
Beaker of boiling water on a hot plate boiling (P)
Pieces of paper being cut into smaller pieces (P)
An ice cube melting. Place in Petri dish. (P)
Mix baking soda and vinegar in a beaker. (C)
Burning a sugar cube. Hold cube with tongs, and hold flame to the cube. Do this
over foil. (C)
2. Note: Address safety precautions for allergies. Instruct students to place a soda
cracker on a paper towel and crush the cracker with their hand.
Ask:
How did the cracker change? (Answers may vary, such as changed shape,
from one piece to many pieces, etc.)
Was this change a physical or chemical change for the cracker? Explain.
(Physical change because it is still a cracker)
Last Updated 05/28/13
Materials:
hot plate (for demonstration, 1 per teacher)
beakers (250 mL and 500 mL, for demonstration,
per teacher)
paper (plain, for demonstration, multiple per
teacher)
scissors (for demonstration, 1 pair per teacher)
ice cube (for demonstration, multiple per teacher)
Petri dish (for demonstration, 1 per teacher)
water (per class)
baking soda (5 cc or 1 tsp., for demonstration, per
class)
vinegar (for demonstration, 50 mL per class)
sugar cubes (for demonstration, 1 per class)
tongs (for demonstration, 1 per teacher)
lighter (long, for demonstration, 1 per teacher)
foil (for demonstration, 1 sheet per teacher)
page 6 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
3. Instruct students to take the second cracker and chew it for one minute. Caution
students not to swallow the cracker. When the cracker is a mushy blob, the students
should begin to notice a sweet taste.
Ask:
What was the first taste you noticed in your mouth? (Salty)
What was the second taste you noticed? (Sweet)
Do you think this change in taste indicates a physical or chemical change?
(Chemical)
Say:
Soda crackers are high in carbohydrates in the form of starch. An enzyme
in saliva begins breaking down the starch into sugar. That is why the
cracker tasted sweet. Two forms of digestion occur in the mouth. Physical
digestion began when you chewed the cracker. Chemical digestion
occurred when the saliva started breaking down the starches.
4. Instruct students to dispose of all crackers in the garbage can.
5. Project the Teacher Resource: Transformation of Energy during Digestion (see
Advance Preparation), and discuss the expectations with students. Review the safety
procedures listed on the page. Answer any question students may have.
6. Divide the class into groups of 4–5, and distribute a copy of Teacher Resource:
Transformation of Energy during Digestion to each group.
7. Instruct students to read through the procedures and construct the data table before
beginning the activity. They are to record all data, observations, and answers to
questions in their notebooks.
soda cracker (2 per student)
paper towel (1 per student)
raw chicken or beef liver (1 piece about thumb nail
size per group, per class)
scissors (1 per group)
beaker (250 mL,1 per group)
hydrogen peroxide ( 75 mL per group, per class)
thermometer or temperature probe (1 per group)
timing device (1 per group)
safety goggles (1 pair per student)
gloves (2 pairs per group)
MSDS for hydrogen peroxide (see Advance
Preparation, 1 per group)
Attachments:
Teacher Resource: Transformation of Energy
during Digestion (see Advance Preparation, 1 for
projection and per group)
Teacher Resource: Transformation of Energy
during Digestion KEY
Safety Notes:
Some students may be allergic to wheat. They should observe the
cracker activity.
8. Facilitate a discussion with students using the Teacher Resource: Transformation of
Energy during Digestion KEY.
Ask groups to:
There are a few safety issues to review with students for the
Identify and distinguish between chemical and physical changes in matter during
digestion. Help students understand that chemical changes do not affect the actual
atoms in a compound, but simply break the bonds that hold them together and
rearrange them to form new substances. They will learn more about the different
arrangements in chemistry. Also, when the chemical bonds break, energy is
released.
Explain the energy transformations that take place during digestion.
digestion activity. They are listed in red at the top of the Handout:
Transformation of Energy during Digestion. You should also
download an MSDS for hydrogen peroxide. Instructions for disposal
are available free on-line. See the Resources and References
above.
Instructional Notes:
Students may have to hold the cracker in their mouth for 1–2 min to
allow time for the carbohydrates to break down into sugar.
Encourage them to fight the urge to swallow. You may need extra
soda crackers (saltines) on hand in case the students swallow
before the sweet taste is noticeable. For the second activity, chicken
livers are cheaper than beef liver. Do not use frozen liver.
Check For Understanding:
The class discussions over the investigation questions are
optimum opportunities for formative assessment.
Misconception:
Students may think chemical change changes the
atoms themselves.
Science Notebooks:
Students record all data, observations, questions and answers in
their notebooks.
ELABORATE – Glucose Model Performance Indicator Part I
Suggested Day 4 (continued)
1. Begin by reviewing the importance of an element, compound, and organic
compounds. All matter is made up of elements, and they combine to form the
compounds that make up the substances on our planet. Organic compounds contain
carbon and make up all living things as well as many products that come from fossil
Last Updated 05/28/13
Materials:
marshmallows (miniature, white, 1 bag per class)
page 7 of 20 Grade 7
Science
Unit: 09
Lesson: 01
Suggested Duration: 5 days
fuels. Photosynthesis and cellular respiration would not be possible without them.
(Refer to the Teacher Resource: Performance Indicator Instructions KEY for
information on administering the assessment.)
Ask:
marshmallows (miniature, colored, 1 bag per group)
toothpicks (round, 24 per group)
Attachments:
What would our planet be like if there was no photosynthesis? Life would
not be possible because we would not have any producers
EVALUATE – Performance Indicator Part II- Illustrating Changes
Teacher Resource: Glucose Model (1 per pair or
group)
Teacher Resource: Performance Indicator
Instructions KEY (1 for projection)
Suggested Day 5
Attachments:
Grade 07 Science Unit 09 PI 01
Create a model of a sugar molecule. Draw a five-pane comic strip to describe how it began as a
carbohydrate and how it was broken down both chemically and physically during digestion into a
sugar molecule. Include the energy transformations taking place throughout the process.
Teacher Resource: Performance Indicator
Instructions KEY (1 for projection)
Standard(s): 7.3B , 7.6A , 7.6B , 7.6C , 7.7B
ELPS ELPS.c.1E , ELPS.c.5F
1. Refer to the Teacher Resource: Performance Indicator Instructions KEY for
information on administering the assessment.
Last Updated 05/28/13
page 8 of 20 Grade 7
Science
Unit: 09 Lesson: 01
Element Comparison
Elements in the Human Body
√
Oxygen (O)
65.0%
Oxygen (O)
47.0%
√
Carbon (C)
18.5%
Silicon (Si)
28.2%
√
Hydrogen (H)
9.5%
Aluminum (Al)
8.2%
√
Nitrogen (N)
3.3%
Iron (Fe)
5.1%
Calcium (Ca)
1.5%
Calcium (Ca)
3.7%
Phosphorus (P)
1.0%
Sodium (Na)
2.9%
Potassium (K)
0.4%
Potassium (K)
2.6%
Sulfur (S)
0.3%
Magnesium (Mg)
2.1%
Sodium (Na)
0.2%
Chlorine (Cl)
0.2%
√
√
©2012, TESCCC
Elements in the Earth’s Crust
12/13/12
page 1 of 1
Grade 7
Science
Unit: 09 Lesson: 01
Building Organic Compounds
H
Hydrocarbons
Formed by: carbon, hydrogen
Examples: propane gas, plastics
C
Carbohydrates and Lipids
O
Formed by: carbon, hydrogen, oxygen
Examples: sugar, fats
Amino Acids and Proteins
N
Formed by: carbon, hydrogen, oxygen,
nitrogen
Examples: gelatin, collagen
Other Amino Acids and Proteins
S
Formed by: carbon, hydrogen, oxygen,
nitrogen, sulfur
Examples: insulin
Nucleic Acids
P
©2012, TESCCC
Formed by: carbon, hydrogen, oxygen,
nitrogen, sulfur, phosphorus
Examples: DNA, RNA
12/13/12
page 1 of 1
Grade 7
Science
Unit: 09 Lesson: 01
Organic Compound Clipart
http://openclipart.org/detail/36109/dna-by-netalloy
http://openclipart.org/detail/328/hand-and-syringe-by-johnny_automatic
©2012, TESCCC
05/28/13
page 1 of 1
Grade 7
Science
Unit: 09 Lesson: 01
Transformation of Energy during Digestion
SAFETY ALERT!!
Wear safety goggles!
Use caution with scissors to avoid injury.
Follow all safety procedures for handling glassware and chemicals.
Do not ingest raw liver. Wash your hands after handling the liver.
Materials per Group:
• raw chicken or beef liver (piece about the size of your thumb nail)
• scissors
• beaker
• hydrogen peroxide (H2O2)(75 mL)
• thermometer or temperature probe (1)
• timing device
• safety goggles
• gloves
Procedure:
1. Create a data table to record the initial temperature and six temperatures taken at 30 sec
intervals.
2. Put on your safety goggles.
3. If you are handling the liver, put on gloves.
4. Cut the liver into smaller pieces with the scissors.
5. Pour 75 mL of hydrogen peroxide into the beaker.
6. Place the one thermometer in the beaker of hydrogen peroxide. Record the initial
temperature.
7. Place the liver pieces in the beaker of hydrogen peroxide.
8. Record the temperature on the thermometers at intervals of 30 seconds for three minutes.
9. Clean up - Pour off the hydrogen peroxide, and dispose of it according to your teacher’s
instructions. Remove the liver from the hydrogen peroxide, and properly dispose of the liver.
10. Answer the questions in your notebook using complete sentences. You do not need to copy
the questions, but the questions must be stated in a format that will allow the reader to
understand which question you are answering.
a)
b)
c)
d)
e)
f)
©2012, TESCCC
How did cutting the liver into smaller pieces represent digestion?
How did placing the liver in the hydrogen peroxide represent digestion?
Use your data to explain what happened to the energy during the investigation.
What type of energy is being released?
Illustrate the energy transformation.
Summarize how this investigation models digestion.
12/13/12
page 1 of 1
Grade 7
Science
Unit: 09 Lesson: 01
Transformation of Energy during Digestion KEY
SAFETY ALERT!!
Wear safety goggles!
Use caution with scissors to avoid injury.
Follow all safety procedures for handling glassware and chemicals.
Do not ingest raw liver. Wash your hands after handling the liver.
Materials:
• raw chicken or beef liver (piece about the size of your thumb nail)
• scissors
• hydrogen peroxide (75 mL)
• thermometer (1)
• stopwatch
• beaker
• safety goggles
• gloves
Procedure:
1. Create a data table to record the initial temperature and six temperatures taken at 30 sec
intervals.
2. Put on your safety goggles and gloves.
3. Cut the liver into smaller pieces with the scissors.
4. Pour 75 mL of hydrogen peroxide into the beaker.
5. Place the one thermometer in the beaker of hydrogen peroxide. Record the initial
temperature.
6. Place the liver pieces in the beaker of hydrogen peroxide.
7. Record the temperature on the thermometers at intervals of 30 seconds for two minutes.
8. Clean up - Pour off the hydrogen peroxide, and dispose of it according to your teacher’s
instructions. Remove the liver from the hydrogen peroxide, and properly dispose of the liver.
9. Answer the questions in your notebook using complete sentences. You do not need to copy
the questions, but the questions must be stated in a format that will allow the reader to
understand which question you are answering.
a) How did cutting the liver into smaller pieces represent digestion?
The cutting of liver into smaller pieces represented the physical break down of
food by chewing.
b) How did placing the liver in the hydrogen peroxide represent digestion?
The hydrogen peroxide represents digestive acids and/or enzymes in the
stomach.
c) Use your data to explain what happened to the energy during the investigation.
Students should have the idea that this models how the chemical energy in food
is released as heat energy. To do this, molecules have to be broken down.
d) What type of energy is being released? Heat energy is being released.
e) Illustrate the energy transformation. Chemical
Thermal
f) Summarize how this investigation models digestion. Answers will vary.
The energy from the Sun was stored in plants through the process of
photosynthesis. The chicken or cow ate plants and transferred about 10% of their
©2012, TESCCC
12/13/12
page 1 of 2
Grade 7
Science
Unit: 09 Lesson: 01
stored energy to themselves. The liver was changed physically when it was chewed.
The liver was changed chemically when it was placed in the hydrogen peroxide.
Chemical changes break bonds and release energy. This energy was released as
heat when the liver was broken down.
©2012, TESCCC
12/13/12
page 2 of 2
Grade 7
Science
Unit: 09 Lesson: 01
Glucose Model
Materials per Model:
white miniature marshmallows (to represent Hydrogen)(12)
miniature colored marshmallows (of one color)(to represent Oxygen)(6)
miniature colored marshmallows (of another color)(to represent Carbon)(6)
toothpicks (to represent bonds)(24)
KEY
________ = Carbon
________ = Oxygen
White = Hydrogen
Background:
Carbohydrates are organic molecules that contain sugars and starches. You will be building one type
of sugar called glucose. Glucose is produced during photosynthesis and acts as the fuel for many
organisms. During cellular respiration, glucose is broken down and releases energy to maintain life as
well as thermal energy. C6H12O6 is the formula for glucose.
Procedure:
1. Choose a color to represent oxygen atoms (O) and another color to represent carbon atoms (C).
List the color code in your KEY above. Build a ring-like structure using six toothpicks, five carbon
atoms, and one oxygen atom.
NOTE: For the examples that follow, dotted is oxygen, striped is carbon, and black is
hydrogen. The toothpicks represent bonds that hold the molecule together and are shown as
black lines. Remember that bonds are the forces that hold atoms together, not physical objects.
You can compare bonds to magnetism where opposites attract or the way electricity flows in a
battery and the + and – (opposites) attract.
2. Using a toothpick to represent the bond, add the sixth carbon atom to one of the carbon atoms
that is next to the oxygen atom.
©2012, TESCCC
05/28/13
page 1 of 3
Grade 7
Science
Unit: 09 Lesson: 01
3. Using toothpicks, attach an oxygen atom to each of the remaining carbon atoms. Notice that
nothing is attached to the original oxygen atom in the ring.
4. Using toothpicks, attach the hydrogen atoms to each of the atoms in the model as shown below.
Notice that nothing is attached to the original oxygen atom in the ring.
5.
One person from each group should gently pick up the model in cupped hands and walk to the
front of the room. Stand shoulder to shoulder forming a line. What you are seeing is a chain of
simple glucose molecules bonding to form a complex carbohydrate.
6.
Each student breaks away from the carbohydrate chain and energetically (not runs) goes back to
their group table. What you are modeling is the breaking up of a large molecule into smaller
compounds and the energy released.
©2012, TESCCC
05/28/13
page 2 of 3
Grade 7
Science
Unit: 09 Lesson: 01
7.
Illustrate your glucose molecule in your notebooks using the element symbols in place of color.
C6H12O6
8.
How did the breaking down of the larger molecule into smaller molecules model digestion?
9.
How did the breaking apart of the carbohydrate chain model an energy transformation?
10. List the advantages and limitations of the glucose model you constructed and the process we
modeled of breaking down a large carbohydrate compound into smaller compounds.
©2012, TESCCC
05/28/13
page 3 of 3
Grade 7
Science
Unit: 09 Lesson: 01
Performance Indicator Instructions KEY
Performance Indicator Part I
Create a model of a sugar molecule. Draw a five-pane comic strip to describe how it began as
a carbohydrate and how it was broken down both chemically and physically during digestion
into a sugar molecule. Include the energy transformations taking place throughout the process.
(7.3B; 7.6A, 7.6B, 7.6C; 7.7B)
1E; 5F
Materials:
marshmallows (miniature, white, 1 bag per class)
marshmallows (miniature, colored, 1 bag per group)
toothpicks (round, 24 per group)
Attachments:
Teacher Resource: Glucose Model (1 per pair or group)
Instructional Procedures:
1. Explain to students that they will be creating a model of a glucose molecule and assembling a
complex carbohydrate chain. They will then break apart the glucose molecules to model the
breaking down of macromolecules. Explain to students that macro means large.
2. This activity is the first part of the Performance Indicator. The rest of the PI will be completed in
the Evaluate piece.
3. Divide the class into groups or pairs, and distribute a copy of the Teacher Resource: Glucose
Model to each group.
4. Monitor and assist students as they create and build their glucose molecules.
5. Instruct students to model a complex carbohydrate (macromolecule) breaking down into smaller
glucose molecules.
6. Instruct students to list the chemical formula for glucose in their notebooks. After they construct
the model and model the breakdown of complex carbohydrates, students should illustrate their
models in their notebooks according the instructions on the Teacher Resource: Glucose Model.
Students will also list the advantages and limitations of the models in their notebooks.\
©2012, TESCCC
05/28/13
page 1 of 3
Grade 7
Science
Unit: 09 Lesson: 01
7. Facilitate a discussion by asking groups to share their models and explain the changes and energy
transformations that took place in the breakdown of their molecules.
Instructional Notes:
Colored marshmallows come in four colors: orange, yellow, green, and pink. Different periods can
have different colors for the O and C atoms to make the materials go further. You may want to presort the colors to make the process function more easily.
Bonding is not covered until chemistry in HS. It is difficult to explain the breaking down of
macromolecules into smaller molecules without discussing bonding. The building of a glucose
molecule is very basic. There is no discussion of or showing the double bond or discussion about how
many bonding sites are on H, C, and O. The activity is simply a kinesthetic modeling of smaller
molecules forming a longer chain and then breaking apart again.
An optional activity would be to allow students create a linear model of glucose.
Science Notebooks:
Students illustrate glucose model using symbols in their notebooks. They will list the advantages and
limitations of the glucose model.
©2012, TESCCC
05/28/13
page 2 of 3
Grade 7
Science
Unit: 09 Lesson: 01
Performance Indicator Part II
Create a model of a sugar molecule. Draw a five-pane comic strip to describe how it began as
a carbohydrate and how it was broken down both chemically and physically during digestion
into a sugar molecule. Include the energy transformations taking place throughout the process.
(7.3B; 7.6A, 7.6B, 7.6C; 7.7B)
1E; 5F
Instructional Procedures:
1. Project the Performance Indicator.
2. Share the Performance Indicator rubric or your expectations with students prior to students
beginning the assessment. Students are to show how large molecules are broken down into
smaller molecules by chemical changes that occur within the digestive system.
3. Instruct students to review the information in their science notebooks from the digestion
investigation with crackers and the Glucose Model activity to draw their comic strip (see
Instructional Notes).
4. Answer any questions students may have regarding the assessment.
5. Monitor and assist students as they complete the project.
6. Allow students time to develop and present their projects to others.
Instructional Notes:
You may need to help students get started, by asking how to personify a piece of food being
mechanically and chemically digested; a carbohydrate compound being broken down into smaller
molecules when the bonds are broken apart; and energy transformations. This can be quite the
humorous conversation.
It is difficult for student to illustrate all the energy transformations throughout the digestive process at
this point. Having students indicate the change from stored energy in the food to heat energy is
sufficient.
Science Notebooks:
Students reference their notebooks to aid in the completion of the PI.
©2012, TESCCC
05/28/13
page 3 of 3