Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 76113
Matter Changes but Mass is Saved!
The focus of this lesson is for students to gain an understanding of how to identify if changes in matter are a physical or chemical change. Also,
students will see that the mass before and after a physical and chemical changes will be the same which supports the Law of Conservation of Mass.
The lesson consists of teacher demonstrations, student lab activities. a writing activity to support student findings and the creation of presentations
for students to share their results and applications of concepts to the real world.
Subject(s): Science
Grade Level(s): 8
Intended Audience: Educators
Suggested Technology: Computers for Students,
Internet Connection, Interactive Whiteboard, Microsoft
Office
Instructional Time: 2 Hour(s)
Resource supports reading in content area: Yes
Freely Available: Yes
Keywords: Physical Change, Chemical Change, Law of Conservation of Mass, Matter
Resource Collection: FCR-STEMLearn Physical Sciences
ATTACHMENTS
Assessment for Physical and Chemical Changes and Conservation of Mass.docx
data table for physical and chemical changes with conservation of mass.docx
Physical and Chemical Changes.docx
LESSON CONTENT
Lesson Plan Template: Learning Cycle (5E Model)
Learning Objectives: What will students know and be able to do as a result of this lesson?
1. Differentiate between physical changes and chemical changes.
2. Explain that mass is conserved when substances undergo physical and chemical changes, according to law of conservation of mass.
3. Apply the Law of Conservation of Mass to the data collected during the physical and chemical change activity.
Prior Knowledge: What prior knowledge should students have for this lesson?
These benchmarks requires prerequisite knowledge from benchmark,SC.4.P.9.1 which in turn used knowledge from SC.K.P.9.1 and SC.2.P.9.1.
The teacher should be able to activate students' prior knowledge through questioning during the engagement portion of the lesson as well as during the explore
activity.
Students are able to recognize that the shape of materials can be changed by cutting, tearing, crumpling, smashing or rolling.(SC.K.P.9.1)
Students are able to investigate that materials can be altered to change some of their properties but not all materials respond the same way to any one
alteration.(SC.2.P.9.1)
Students should be able to identify familiar changes in materials that result in other materials with different characteristics, such as decaying animal or plant matter,
burning, rusting and cooking.(SC.4.P.9.1)
Students should understand that changes in the states of water may result in a liquid, gas(water vapor) or solid(ice) but each state is still considered water and not
a new substance.
Guiding Questions: What are the guiding questions for this lesson?
page 1 of 5 The teacher will walk around during the activity to each group and ask students the guiding questions.
If students answer the questions incorrectly, other students in the group can help with answering the questions so it becomes a team effort.
Based on the students answers the teacher can identify the concepts that the students are having difficulty with and will be able to guide them to a better
understanding of the concept.
1. Explain the difference between a physical change and chemical change and identify what types of evidence indicates that specific change has occurred.
Answer: Physical change is when the form or appearance of matter changes but does not change the substance into new substances. For example, ice is water
and when it melts it is still water. Some examples of processes that result in physical changes are tearing, slicing, crushing, grinding, condensation, evaporation,
freezing and sublimation. The key to identifying a physical change is the substance is still the same even though it may be a different shape or state of matter.
Chemical changes result in a change in matter that produces one or more new substances with different properties. The new substance can't be changed back to
the original substance. Evidence of chemical changes include change in temperature, bubbling which indicates gas production, formation of a precipitate, and
color change (can't change back to original color).
2. Explain the Law of Conservation of Mass and how this law can be applied to physical and chemical changes.
Answer: Law states that when matter goes through a physical or chemical change the amount of matter stays the same before and after the changes occur
3. How can you determine if the mass of the original substances is the same after they undergo a physical and/or chemical changes?
Answer: Before doing a physical or chemical change find the mass of all substances in the before and after the change occurs and then calculate the change in
mass. Mass should be conserved during both physical and chemical changes so there should not be a change in mass. If there is a change, the students should try
and figure out where mass is being lost.
Engage: What object, event, or questions will the teacher use to trigger the students' curiosity and engage them in the concepts?
Engagement:
Put students in groups of four and allow them to share their observations and and answers to questions (listed below) before you ask students from each group to
share.
Idea: Give each group a white board and marker to write their group's answers.
Demonstration:
The teacher will show the students two demos: burning paper in a 1000 ml beaker (do in a fume hood if available)and place chocolate chips in a beaker on a hot
plate set on low heat.
Students should make observations during each demo and record them in their science journal and answer the following questions.
Questions:
1.What happens to paper when it is burned? Is this a physical or chemical change? Explain
Answer: Ashes are produced and gases are given off which indicates a chemical change since the ashes can't be changed back to the original paper.
2. Do you think the mass of the original paper is the same as the mass of the remains of the paper?Why or why not?
Answer:The mass of the products(ashes) of this chemical change is less than the original paper since gases(have mass) which were produced during the change
were given off to the surroundings.
3. What happens to the chocolate chips that were placed in the container on the hot plate? Is this a
physical or chemical change? Explain.
Answer: The heat from the hot plate caused the chocolate chips to melt which is still chocolate so this is a physical change. If the melted chocolate is allowed to
cool it will become solid chocolate which has a different shape from the chips but its chemical form is still the same.
4. Do you think that the mass of the chocolate chips the same as the melted chocolate? Explain your answer.
Answer: If we measured the mass of the chips and then the mass of the melted chocolate, the masses should be the same (or very close).
Note:The teacher should NOT correct the students' misconceptions at this time and revisit the questions during the discussion of the lab activity. Students should be
given time to revise their answers after they complete the lab activity and before the class discussion of the lab.
Explore: What will the students do to explore the concepts and skills being developed through the lesson?
The students will complete a lab activity where they will investigate how to determine if matter undergoes a physical or chemical change and whether the amount
of mass is conserved during that change, which supports the Law of Conservation of Mass.
Students should be placed in lab groups of four students.
This activity consists of six different lab stations and students will rotate to each station every 10 minutes.
Before beginning this activity, the teacher should go over the procedures for each station to ensure the students understand the directions.
The teacher should move around the room during the lab activity and ask individual students and groups, the guiding questions to ensure that they are grasping the
concepts.
While completing this activity, the students should be gaining an understanding of what type of evidence indicates a physical or chemical change.
I find that students have a difficult time understanding the Law of Conservation of Mass, so the teacher should guide them by asking them questions about their
mass data and why they might be getting a change in mass. The stations have been set up with the students doing the same activity twice but one is in a closed
system and the other is an open system. Some students will pick up on this right away but other students will need some guidance.
A data table with sample data can be found with the student's data table attachment.
The students should work together as a team to complete the analysis questions.
Each student must complete the following sections but they should work together as a team.
1. Problem Statement
2. Hypothesis
3. Data Table
4. Analysis Questions
Safety Precautions:
1. Don't let students handle the dry ice. The teachers should wear protective gloves when handling the dry ice and use a hammer to break it into pieces that will fit in
the small water bottle.
2. The teacher should explain to the students the safe way to use a hot plate and stress that they must wear a hot mitt when removing the beaker.
page 2 of 5 3. Students should NOT eat anything of the substances in this lab.
4. Students should clean up the station before moving on to the next station.
5. The teacher should come up with procedures for students to follow when cleaning up at each station
Explain: What will the students and teacher do so students have opportunities to clarify their ideas, reach a conclusion or
generalization, and communicate what they know to others?
Give students the opportunity to go back to the questions from the engagement and revise their answers.
Ask students to share any changes that they made to any of the answers.
Have a class discussion about the results of the lab activity and call on students from each group to share their results and answers to the analysis questions.
The teacher needs to make sure that students are able to identify and explain physical and chemical changes and apply the Law of Conservation to each change.
Students will make sure that they have completed each of the following sections of the lab report: problem statement, hypothesis, data table, and analysis
questions.
Students will complete a claim, evidence reasoning for the conclusion for this lab activity.
CONCLUSION WRITING.docx
Elaborate: What will the students do to apply their conceptual understanding and skills to solve a problem, make a decision,
perform a task, or make sense of new knowledge?
Students will research physical and chemical changes that occur in their daily lives and create a presentation using technology such as Power Point or Prezi(free
resource for teachers)
The presentation must also address the application of the Law of Conservation of Mass to each physical and chemical change.
Students must include at least three examples of both physical and chemical changes in their presentation.
Presentations should be creative and must be students' original work.
Summative Assessment
After a class discussion on the lab activity, students will complete a claim, evidence and reasoning which will be considered the conclusion for the lab activity which
shows an understanding of physical and chemical changes and how these changes support the Law of Conservation of Mass. The following link will show a
rubric that can be used to grade the Claim, Evidence, and Reasoning:
CONCLUSION WRITING.docx
Once students have completed the lab activity, class discussion and conclusion, they will complete an assessment on physical and chemical changes and the Law of
Conservation of Mass.The assessment is in the attachment section.
Formative Assessment
1. The teacher will ask students probing questions during each portion of the lesson.
2. During the engagement portion of the lesson, the questions will be about the demonstration and during the rest of the portions the teacher will ask the guiding
questions.
3. Any student's misconceptions should not be cleared up until after the students complete the activity.
Engagement:
1. Put students in groups of four and allow them to share their observations and and answers to questions before you ask students from each group to share.
Idea: Give each group a white board and marker to write their groups answers.
Sample questions:
1.What happens to paper when it is burned? Is this a physical or chemical change? Explain
Answer: Ashes are produced and gases are given off which indicates a chemical change since the ashes can't be changed back to the original paper.
2. Do you think the mass of the original paper is the same as the mass of the remains of the paper? Why or why not?
Answer:The mass of the products(ashes) of this chemical change is less than the original paper since gases(have mass) which were produced during the change
were given off to the surroundings.
3. What happens to the chocolate chips that were placed in the container on the hot plate? Is this a
physical or chemical change? Explain.
Answer: The heat from the hot plate caused the chocolate chips to melt which is still chocolate so this is a physical change. If the melted chocolate is allowed to
cool it will become solid chocolate which has a different shape from the chips but its chemical form is still the same.
4. Do you think that the mass of the chocolate chips the same as the melted chocolate? Explain your answer.
Answer: If we measured the mass of the chips and then the mass of the melted chocolate, the masses should be the same (or very close).
Note: The teacher should NOT correct the students' misconceptions at this time and revisit the questions during the discussion of the activity. Students should be given
time to revise their answers after they complete the activity.
Guiding Questions:
The teacher will walk around during the activity to each group and ask students the guiding questions.
If students answer the questions incorrectly, other students in the group can help with answering the questions so it becomes a team effort.
Based on the students answers the teacher can identify the concepts that the students are having difficulty with and will be able to guide them to a better
understanding of the concept.
1. Explain the difference between a physical change and chemical change and identify what types of evidence indicates that specific change has occurred.
Answer: Physical change is when the form or appearance of matter changes but does not change the substance into new substances. For example, ice is water
and when it melts it is still water. Some examples of processes that result in physical changes are tearing, slicing, crushing, grinding, condensation, evaporation,
freezing and sublimation. The key to identifying a physical change is the substance is still the same even though it may be a different shape or state of matter.
Chemical changes result in a change in matter that produces one or more new substances with different properties. The new substance can't be changed back to
the original substance. Evidence of chemical changes include change in temperature, bubbling which indicates gas production, formation of a precipitate, and
color change (can't change back to original color).
2. Explain the Law of Conservation of Mass and how this law can be applied to physical and chemical changes.
Answer: states that when matter goes through a physical or chemical change the amount of matter stays the same before and after the changes occur
3. How can you determine if the mass of the original substances is the same after they undergo a physical and/or chemical change?
page 3 of 5 Answer: Before doing a physical or chemical change find the mass of all substances in the before and after the change occurs and then calculate the change in
mass. Mass should be conserved during both physical and chemical changes so there should not be a change in mass. If there is a change, the students should try
and figure out where mass is being lost.
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
Students with an Individual Education Plan (IEP) or students with specials needs can be accommodated by having these students work in groups with higher level
students that will assist them in completing the lab activity.
The teacher can also assist these students by monitoring their progress in the groups and ensure that they are not being left out the group.
Groups of students should include a variety of levels.
The teacher can assists students who appear to be having trouble understanding the concepts.
Extensions:
A possible extension for this activity is for students to to design their own experiments that differentiate between physical and chemical changes and the application of
the Law of Conservation of Mass.
Suggested Technology: Computers for Students, Internet Connection, Interactive Whiteboard, Microsoft Office
Special Materials Needed:
Teachers can purchase dry ice at most grocery stores.
Teachers need to wear hand protection when handling the dry ice.
Teachers can use a hammer to break up the dry ice and they must place the pieces in the water bottle for the students.
Balloons that will fit over the opening of the water bottles
Vinegar
Baking Soda
Small Empty Water Bottles
Triple Beam or Electronic Balances
Sugar Cubes
Ice Cubes
600 ml Beakers
Water
Alka Seltzer Tablets
Hot Plates
Oven Mitts
Chocolate Chips
Further Recommendations:
This activity can be completed as an open inquiry for higher level students or entire class.
Make sure students understand the procedures at each station of the lab before they begin the lab activity.
Teachers need to come up with procedures for students to clean up each station before they move on to the next station.
The time for rotations might need to be adjusted based on students in a particular class.
Teachers could put the data table up on an interactive board and have students share their findings during the discussion of the lab activity.
Additional Information/Instructions
By Author/Submitter
This lab activity can be used as an open inquiry by having students design their own procedures at each station.
SOURCE AND ACCESS INFORMATION
Contributed by: Martha Schrager
Name of Author/Source: Martha Schrager
District/Organization of Contributor(s): Miami-Dade
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:
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.
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