Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 30583
Change or Not - Same Mass
The students make observations and take the mass of various structures constructed by the teacher. They rearrange the structures and measure
the mass again. During the whole class discussion the students come to understand that during a chemical or physical change the mass is
conserved.
Subject(s): English Language Arts, Science
Grade Level(s): 8
Intended Audience: Educators
Suggested Technology: Computer for Presenter,
Overhead Projector
Instructional Time: 1 Hour(s) 30 Minute(s)
Freely Available: Yes
Keywords: Law of conservation of mass, physical change, chemical change, mass, model, matter, atom
Instructional Design Framework(s): Direct Instruction, Structured Inquiry (Level 2)
Resource Collection: CPALMS Lesson Plan Development Initiative
ATTACHMENTS
REV.Teacher Resources law of conservation.docx
LESSON CONTENT
Lesson Plan Template: General Lesson Plan
Learning Objectives: What should students know and be able to do as a result of this lesson?
Students will:
1. be able to describe physical and chemical changes and give support with examples.
2. understand that mass is conserved (stays the same) when substances undergo physical or chemical changes.
Prior Knowledge: What prior knowledge should students have for this lesson?
This lesson reinforces the previous lesson on physical and chemical changes. The focus of this lesson is to demonstrate that the mass remains the same when matter
undergoes a physical or a chemical change.
Students should:
understand that all matter is made up of atoms.
be able to differentiate between physical and chemical changes.
be able to define physical and chemical changes.
be able to give examples of physical and chemical changes.
Guiding Questions: What are the guiding questions for this lesson?
Guiding Questions
1. How do you define change? (To make the form, nature, content of something different from what it was. To transform or convert.)
2. How do you know when something has changed? (The physical appearance or chemical make-up is different.)
3. Differentiate between physical and chemical changes. (Physical change – The appearance or form of a substance has changed but no new substance is produced.
Chemical change - a change in matter that produces one or more new substances.)
page 1 of 3 4. What is mass? (A measure of how much matter is in an object. Total sum of atoms in an object or substance.)
Teaching Phase: How will the teacher present the concept or skill to students?
The teacher will begin the lesson with the chemical and physical changes t-chart and melting butter probe. After the discussion the teacher will review classroom and
lab safety rules.The class will then read directions for the activity as a group. One person from each group will collect materials. students follow directions and complete
assignment. When students are finished with activity the second person in the group will return materials. During the assessments and activity the teacher must monitor
each student and/or group.
Guided Practice: What activities or exercises will the students complete with teacher guidance?
This is not a food lab, and safety rules should be reviewed.
Candy should be discarded at the end of the lab and students should wash hands before they leave.
Check for allergies. Modeling clay or LEGOs could be used as an alternative to candy.
Materials may be reused or discarded. Candy may get a bit sticky from handling.
In this lab, the teacher uses candy and toothpicks to model atoms. The teacher must set up prior to students arriving.
Use toothpicks and various shapes and types of soft candy (gummy bears, jellybeans, marshmallows, Starbursts, etc.) to create different structures. Students must be
able to easily take them apart and rearrange them into different shapes. They can be as creative as they wish. Students will work in cooperative pairs to complete the
activity.
Materials for each pair:
Clear sandwich bags with 4 different structures made from toothpicks and soft candy
Balance
Paper
Pencil
Ruler
Colored pencils
Procedure:
1. Take all of the structures out of the sandwich bag.
2. Place all of the structures on the balance at the same time and measure the mass.
3. Create a data table and record the mass in the data table.
4. Record each of the structures on the table. Make observations by listing two similarities and two differences. Draw and color the structures.
5. Take apart and rearrange the structures. Be creative!
6. After you have rearranged them, measure total the mass again. Remember to place all structures on the balance at the same time. Record the mass in the data
table.
7. Draw and color the rearranged structures.
8. Place all the structures in the sandwich bag and prepare for clean-up.
Independent Practice: What activities or exercises will students complete to reinforce the concepts and skills developed in the
lesson?
Students will measure the mass of the structures at the beginning and at the end of the activity and record the data in a data table. They will make observations by
drawing before and after pictures of the structures and describing similarities and differences.
Students will answer the questions individually and share answers during whole class discussions.
1. Ask students to define a model. (A model is a representation of a complex object or process, used to help people understand a concept)
2. Ask students to explain what the toothpicks and candy represented. Lead the discussion so that the class understands that the candy and tooth picks can be used to
represent matter, and that matter is made of atoms.
3. The students share their data with the entire class. The teacher will create a data table on the overhead or whiteboard with columns for "Mass Before" and "Mass
After." Each group adds their data to the table.
Whole class discussion
1. Ask students to explain the data. Students should see that the mass is the same in the before and after column of each group. They should start to realize that even
though the appearance of the structure changed, the mass was the same.
2. If the mass is not exactly the same after the structures were rearranged, ask students to explain any discrepancies in the data. Possible explanations:
Some of the candy may have been a bit sticky, and may have stuck to someone's hand or the table.
There may have been human error in reading and operating a balance.
There may mechanical problems with the balance.
3. Ask the students what process was represented when the candy was rearranged (a change). We are not going to classify changes as physical or chemical in this
lab. Ask the students to state what happened to the mass before and after the change took place. The students should understand that the mass stays the same
before and after the change.
Closure: How will the teacher assist students in organizing the knowledge gained in the lesson?
From the discussion, the teacher and students come up with three facts that are essential to the lesson.
1. The Law of Conservation of Matter states that matter is not created or destroyed in any chemical or physical change.
2. The mass stays the same before and after a change because the sum of the atoms does not change.
3. A model is a representation of a complex object or process used to help people understand a concept.
Students write the three facts in their science notebook. The students will then read it to themselves five times to process. Then, without looking at their notebooks, the
students take turns repeating the facts to their shoulder/face partner until all of the facts have been verbalized by all of the students.
Summative Assessment
At the end of the lesson, the students will answer the following questions.
1. Define the law of conservation in your own words. Students may use diagrams to help explain the answer.
2. Explain how the Law of conservation of mass can be demonstrated in the following situations:
Baking a cake
Shredding paper
Formative Assessment
page 2 of 3 1. Students create a t-chart and classify the following as a physical change or a chemical change. Students should be able to justify answers.
Cracking eggs (physical), frying eggs (chemical), toasting bread (chemical), slicing bread (physical), lighting a match (chemical), rusting nails (chemical), melting
butter(physical), breaking glass (physical), boiling water (physical), baking a cake (chemical), cutting the grass (physical), fireworks (chemical), and digesting food
(chemical).
2. Melting Butter Probe - Students will complete this probe individually and then share answers during whole class discussion.
Leslie took 40 mg of solid butter out of the refrigerator, put it in a closed container, and placed it in the microwave. When she took out the melted butter there
seemed to be less butter in the container. She turned to her sister and said, "There was more butter in the container before I melted it." Her sister said, "No, it's the
same amount." With whom do you agree and why?
Feedback to Students
The formative assessments will take place at the beginning of the class. Students will get feedback as the questions are discussed during the whole class discussion.
1. Physical or Chemical Changes: Students will work cooperatively to organize the list in t-chart. The teacher may also use pictures of the items.
2. Melting Butter Probe: Students work individually. This allows the teacher to assess their individual understanding. The teacher will process this probe with the whole
class once the monitoring is complete.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
1. Students with vision issues may be given a handout with larger print.
2. A data table could be created in advance for students with physical disabilities.
3. Make sure the tables in classroom are spaced to accommodate students in wheelchairs.
4. Give oral directions in addition to written ones.
5. ESE students can be given a table with one possible combination, and then they have to come up with the rest on their own.
6. Higher-level students may create an activity that proves that mass remains unchanged in a chemical or physical change.
Extensions: Students keep a journal and document the ways that mass is conserved in their every day lives.
Suggested Technology: Computer for Presenter, Overhead Projector
Special Materials Needed:
Teacher must have candy structures ready prior to the start of class. Materials may be reused.
Materials for each student pair:
Clear sandwich bags with four different structures made from toothpicks and soft candy
Balance
Paper
Pencil
Ruler
Colored pencils
SOURCE AND ACCESS INFORMATION
Contributed by: Joan McGhee
Name of Author/Source: Joan McGhee
District/Organization of Contributor(s): Seminole
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.8.P.9.1:
SC.8.P.9.2:
LAFS.68.RST.1.3:
Description
Explore the Law of Conservation of Mass by demonstrating and concluding that mass is conserved when substances
undergo physical and chemical changes.
Differentiate between physical changes and chemical changes.
Follow precisely a multistep procedure when carrying out experiments, taking measurements, or performing technical
tasks.
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