Christina Bell
Ed 415
Dr. Duncanson
April 6, 2010
Law of Conservation of Mass
Content Standards: 3.1 Materials have properties that can be identified and described through the use
of simple tests.
Concept: According to the Law of Conservation of Mass, mass cannot be created nor destroyed, even
though it may undergo change.
Learner background: The students should have a basic understanding of the concept weight: they
should know, for example, that a book is heavier than a pencil. The students also know what a physical
and chemical change is based off last week’s lesson. The students are not clear on how mass and weight
are two different terms, and how the Law of Conservation of Mass plays a big role in clarifying these
differences.
Student Learning Objectives:
Psychomotor: After being given the appropriate materials, the students will conduct physical and
chemical change experiments relating to the Law of Conservation of Mass.
Cognitive: After experimentation, students will discover that the mass of a substance can neither be
created nor destroyed, even though it may undergo change.
Affective: After evaluating the student’s learning comprehension, the students will be enthusiastic about
using mass and weight- related manipulatives.
Assessment:
Cognitive: Worksheets and science journals will be evaluated throughout the class and will be handed in
to the teacher at the end of class.
Affective: Students will show enthusiasm towards the topic of the law of conservation of mass by the
end of the lesson, by raising their hands for enjoyment, non-enjoyment, and indifference.
Psychomotor: Class members will complete the all experiments by participating in groups and in class
discussions evaluated by the teacher.
Materials/Resources:
General materials: Pencil, pen, dry- erase marker/chalk, science journal, piece of paper
Activity 1: SCHOLASTIC’S THE MAGIC SCHOOL BUS GETS BAKED IN A CAKE: A Book About
Kitchen Chemistry” by: Joanna Cole
Activity 2: 255 grams of water, 25 grams of sugar, scale, spoon, glass (in each group)
Activity 3: http://www.brainpop.com/science/matterandchemistry/conservationofmass/ (video on
website)
Activity 4: ice cubes, Ziploc bags, scale (in each group)
Activity 5: scale, one-hundredth cubic block & one single hundred cubes, ice-cream ice-cream scoop,
Ziploc Bags, 255 grams of water, glass, 25 grams of salt, spoon, chemical equation worksheets
Learning Activities:
Intro/Initiation: (5 min)
Activity 1: Magic School Bus Book Picture Walk (10 min)
Activity 2: Sugar in dissolving water experiment/presentations: (25 min)
Discussion on Law of Conservation of mass using video: (10 min)
Activity 3: Ice Cubes experiment: (20 min)
Activity 4: Four Assessment Experiment: (20 min)
Homework/Lesson Review/wrap-up: (10 min)
Initiation:
Motivation: I hope this class is ready to have fun and get experimenting with mass and weight.
Recall: Based off last week’s lesson, can anyone tell me what a physical change is? What is a chemical
change?
New Learning: Today’s lesson will focus on the topic of the Law of Conservation of Mass. We will
experiment and manipulate materials in order to better understand what happens when the Law of
Conservation of Mass is applied to everyday objects. We will use our knowledge of physical and
chemical changes to help aid us in the experiments.
Future Learning: We will use this newly acquired information to better understand how the Law of
Conservation of Mass is related to next week’s science lesson on the Law of Conservation of Energy.
Lesson Development:
EngageThe teacher will ask the students to verbally define what a physical change is, what a chemical change
is?
The teacher will look at several pictures and read a few pages (a book picture walk) from
“SCHOLASTIC’S THE MAGIC SCHOOL BUS GETS BAKED IN A CAKE: A Book About Kitchen
Chemistry” by: Joanna Cole.
The teacher will hold a brief class discussion about the physical and chemical changes that occur in this
book.
The teacher will ask: How do you think physical and chemical changes relate to the topic of mass and
weight?
Student Answer/Misconception: All objects are made of matter. Depending on the physical or chemical
state of an object, the mass or weight can stay the same or increase in mass or weight.
Misconception 1: Mass and weight are the same thing; Weight and mass are often used
interchangeably.
Explore- Now for the fun part! Students will now experiment with the materials the teacher has put on
each table. The teacher has already given each group a glass cup of water (255 grams). The teacher has
already measured out 25 grams of sugar. The students will mix the sugar into the glass for 1 minute and
observe what happens. The group will each fill out Worksheet 1 Misconceptions; the student will circle
the correct multiple choice answer (D) and provide an explanation on why they chose that answer. The
teacher will walk around the classroom and assess each group based on student participation.
Explain- Now the each group will present their results in front of the class. The teacher will ask each
group:
1)What was your answer? Why did your group choose this answer? What kind of change is this: a
physical or chemical?
Misconception 2: The teacher will bring up that it is a common misconception for students to think that
when sugar is added to water and dissolves, the mass and weight of the water will stay the same
because the sugar is clearly NOT visible.
The teacher will explain and clarify the correct answer/misconception: That although the sugar dissolved
in the water, it did not disappear; therefore after the sugar is added, the water will weigh more.
The teacher will introduce The Law of Conservation of Mass using the following website video:
http://www.brainpop.com/science/matterandchemistry/conservationofmass/
This website explains the Law of Conservation of Mass. The students will watch the video and realize
that mass cannot be created or destroyed. The students will take notes in a science journal as they are
watching and listening to the video.
New Vocabulary: Law of Conservation of Mass, Reactants, Product, ANTOINE LAVOISIER
-The teacher will use this vocabulary and relate it back to CLARIFY Misconception 1 & 2.
Elaboration- To further explore the topic of the Law of Conservation of Mass, the students will conduct
an experiment that will answer the following question:
Does the melting of ice violate the Law of Conservation of Mass? Why or why Not?
The teacher will provide each group with a scale, plastic Ziploc bag, and an ice cube. The students will
put the ice cube in the plastic Ziploc bag and weigh it on the scale immediately. The measurement (in
grams) is recorded in a science journal. The students will wait for the ice cube to completely melt and
will weigh the melted ice cube on the scale. Results are recorded in a science journal.
The students will individually answer the following HOT and LOT questions:
What did you notice about weight of the ice cube after weighing on the scale?
-Stayed the same weight: mass did not change.
What kind of change did the ice cube undergo?
-Physical: changed from a solid to a liquid.
Does the melting of ice violate the Law of Conservation of Mass? Why or why Not?
-No its does not violate the Law of Conservation of Mass because during a physical or chemical
change, mass cannot be created nor destroyed; therefore when the ice melts and become liquid
water, no mass is lost.
NOTE: The experiment must be done at a fast pace because the ice cubes will melt fairly quickly.
The class will now hold a discussion of the ice cube experiment. The teacher will listen to student
answers and explanations to the questions. Teacher will clarify student answers.
EvaluationEach student will go back to their groups and will participate in a “Process Circus” in order to
demonstrate understanding of the Law of Conservation of Mass. The “Process Circus” consists of a series
of four experiments that the student groups will participate in. ALL EXPERIMENT RESULTS are recorded
individually in the student’s own science journal. The students will be at each station for about 5
minutes.
Station 1: Cubical Counting Blocks: Students will weigh the hundredth block cube and one-hundred
small cubes in order to demonstrate the Law of Conservation of Mass.
Station 2: Ice Cream Melt: Students will repeat the ice cube experiment except substitute the ice-cube
in the Ziploc bag for a scoop of ice cream. The teacher has a mini fridge at this station that will keep the
ice cream cool in between sessions. Students can use body heat (holding the bag in hands) to melt the
ice cream at a faster pace.
Station 3: Law of Conservation Chemical Equation: The students must solve the chemical equation
relating to the Law of Conservation of Mass.
Write a word equation:
Write the masses of
each substance given
in the question
hydrogen + oxygen
4g
?
water
36 g
Use the law of conservation of mass
(mass of reactants = mass of
products)
4 + ? = 36
Solve to find the missing value
? = 36 - 4
? = 32
So 32 grams of oxygen were used
Station 4: Salt Dissolving in Water: The students will weigh be given a glass filled with 255 grams of
water. The students will add and mix 25 grams of salt to the water until it dissolves. The students will
weigh the water and salt mixture using a scale and record the results.
Closure: Alright, you students have learned a lot about the topic of the Law of Conservation of Mass.
After all experiments are complete the students will be able to answer the following questions on a
piece of paper to be handed in:
1. Is the change you observed at Station 1, 2, 3, 4 a physical or chemical change? How do you
know? Write an explanation after reflecting back on each experiment.
2. What is a common misconception that you students tend after reflecting back on Activity 2
(sugar dissolving in water)?
3. Based on the lesson plan, what is the main concept you students should have learned?
4. What is the difference between melting and dissolving?
Now by a raise of hands, how many of you were interested in this lesson? How many of you did not
enjoy the lesson? How many students are indifferent about this lesson? Now don’t forget to do the two
homework assignments for next class. All worksheets, papers, and science journals are collected and
assessed based on completion by the teacher.
*Safety Note: Be sure to keep an eye on the students, because any one of the materials provided could
be harmful if misused. Be aware of ice cube puddles or sugar that may be on the floor.
Here are some other examples of chemical reactions:
raw egg
becomes
cooked
egg
cake mix
becomes
cake
paper
becomes
ash
steel
becomes
rust
http://www.saskschools.ca/curr_content/science9/chemistry/lesson8.html
What Happens to Mass During Physical and
Chemical Changes?
Imagine weighing an ice cube. After the ice cube
melts, you weigh the liquid that formed. Which state
weighed more—the solid or the liquid? Neither—they
have the same mass. During a chemical or physical
change, mass cannot be created or destroyed. This is the
law of conservation of mass. Conserve means “to keep
the same.” When the ice melts and becomes liquid water,
no mass is lost.
Law of Conservation of Mass:
Mass cannot be created or destroyed.
http://classjump.com/stubblefield/documents/9885570497.pdf