Primary Type: Lesson Plan
Status: Published
This is a resource from CPALMS (www.cpalms.org) where all educators go for bright ideas!
Resource ID#: 72646
"Weight! What's the Mass?"
The lesson will teach students the difference between mass and weight with a hands-on activity and instruction. Students will simulate a reduction in
gravity (i.e. a reduction in an object's weight) using water's buoyancy. The research question that the students will address is: "Will an object's
mass and weight differ in and out of water?"
Subject(s): Science
Grade Level(s): 8
Intended Audience: Educators
Suggested Technology: Computer for Presenter,
Basic Calculators, LCD Projector
Instructional Time: 45 Minute(s)
Resource supports reading in content area: Yes
Freely Available: Yes
Keywords: mass, weight, triple-beam balance, spring scale, grams, Newtons, variables, graph, astronaut
Resource Collection: FCR-STEMLearn Diversity and Ecology
ATTACHMENTS
Mason and Jb fish.docx
wet and dry weight lab.docx
wet dry key.docx
LESSON CONTENT
Lesson Plan Template: Confirmatory or Structured Inquiry
Learning Objectives: What will students know and be able to do as a result of this lesson?
1. Students will simulate a reduction in gravity (ie: a reduction in the object's weight) due to water's buoyancy.
2. Students will be able to describe the difference between mass and weight.
3. Students will measure and record data of the mass of solid objects (g) as well as the weight of solid objects (Newtons), while the objects are dry and wet (i.e.
submerged).
4. Students will use a triple-beam balance to measure the mass of the objects in grams and will use a spring scale to measure weight in Newtons (optionally, the
teacher can use grams as the measurement for weight to facilitate direct comparisons to mass measurements).
5. Students will calculate the difference between the dry weight and wet weight of the objects.
6. Students will label and plot/graph data using bar graphs.
7. Students will identify the variables and constants/controlled variables.
8. Students will understand why astronauts train in water as to create an environment similar to outer space.
Prior Knowledge: What prior knowledge should students have for this lesson?
The concepts of mass and weight are complicated and potentially confusing to elementary school students. Hence, the more familiar term of "weight" is
recommended for use to stand for both mass and weight in grades K-5.
By grades 6-8 students are expected to understand the distinction between mass and weight and use them appropriately.
Students will know simple math: addition and subtraction.
Students will know how to measure, record, and graph data; as well as label a graph.
Students will know how to calibrate and use a triple-beam balance and measure objects in grams.
page 1 of 4 Students will have been taught to identify variables and constants/controlled variables in an experiment.
Students will have been taught how to investigate a research question and write a hypothesis statement, using "if, then, because".
Students who have been in water and carried a friend have experienced that it is easier to carry a friend as they feel lighter compared to out of the water.
Students will have been taught the principle of buoyancy.
Guiding Questions: What are the guiding questions for this lesson?
1. Why do astronauts train in water?
2. How does water cause an object to become bouyant?
3. How does mass differ from weight?
4. What is used to measure mass?
5. What is used to measure your weight?
6. How is measuring your weight different from measuring weight in a science class?
Introduction: How will the teacher introduce the lesson to the students?
Complete the Build a Bar Graph probe. Students will be presented a formative assessment probe on the LCD projector: "June and Mason went fishing".
Students will be provided with 2 sticky notes, and they will be instructed to sign their names on the backsides of the notes.
Students will read the assessment probe quietly and choose answer A, B, or C. They will write the answer on the front side of the sticky note.
2 large blank posters will be labeled A, B, C at the bottom. One poster will be labeled Part 1 and the other will be labeled 2 (A, B, and C will create the categories
for the "columns" (stacked sticky notes) of the bar graph). The posters will be hung in the front of the classroom. Students will be dismissed by rows/tables to place
their sticky notes on the answers that they chose. Students will be instructed to place their sticky notes vertically to create a bar graph for the build a bar graph
probe "June and Mason went fishing."
The teacher will be able to make a quick assessment on their prior knowledge about Mass and Weight by noting the number of correct answers on the bar graph. If
there is a large number of incorrect answers, the teacher will remind students that mass measures the amount of matter in an object, and weight measures the
gravitational force's effect on an object.
The teacher will pass out the handout "Weight! What's the Mass" lab (attached) to students, and the research question will be presented. Does an object's mass
and weight differ in and out of water?
Students will write a hypothesis statement using the "If-then-because" format to address the research question.
For example: If you measure an object's mass and weight in and out of water, then the mass of an object will not change, but the weight will decrease, because
the water pushes up on the object causing it to become buoyant.
The teacher may ask various students to read their hypothesis statements aloud and make comments such as "Thanks for your response. Let's complete this lab
and see if your hypothesis is supported or not."
While the students are completing the "Weight! What's the Mass" lab the teacher will be circulating around the lab stations asking formative questions:
1. How does a spring scale work?
2. What is the role of gravity on the object?
3. Why does the water level rise when an object is submerged in it?
4. Why does water cause the weight of an object to change?
5. Why is it so easy to carry a friend/relative in water as compared to out of water?
The teacher will listen to responses from students and respond with the correct answers:
1. A spring scale is a scientific tool that has a hook and a spring; when objects are hung from them, the force of gravity's effect on the mass is measured.
2. Gravity is the downward force applied to all objects with a mass.
3. When the object is submerged in water, the object forces the water to be displaced causing the water level to rise.
4. The water pushes up on the object causing the object to become more buoyant, thus decreasing the weight of the objects.
5. When an object is submerged in water its weight decreases making it easier to carry a friend in water compared to out of water.
**The formative assessment "June and Mason went fishing" is attached with a key
Investigate: What question(s) will students be investigating? What process will students follow to collect information that can be
used to answer the question(s)?
Research Question: Will an object's mass and weight differ when in and out of water?
Please refer to the "Guiding Questions" section for more detail.
**The "Weight! What's the Mass?"" lab is attached (Key is also attached) with the materials needed and the procedures the students need to follow.
Analyze: How will students organize and interpret the data collected during the investigation?
The summative assessment/investigation will be completing the "Weight! What's the Mass?" lab in groups of 2-3 students.
The teacher will assign a due date (3-4 days) and will collect the "Weight! What's the Mass?" lab assessment. The teacher will grade the lab within a week using the
attached key.
The teacher will grade:
Hypothesis statement: Make sure the student used "If, then, because" format. (10 pts)
Questions 1-8: Each question is worth 5 pts, and teacher may use her/his discretion for partial credit. (40 pts)
2 graphs will be graded; each graph will be worth 25 pts.
Student graphs need to include a Title, the Variables will be labeled properly on the "X and Y" axis, and the Units of measurement are will be included. The teacher
may use his/her discretion for partial credit.
A key is attached so that the teacher can determine if the students have reached the learning objectives for the lesson.
Closure: What will the teacher do to bring the lesson to a close? How will the students make sense of the investigation?
The teacher will grade "Weight! What's the Mass?" lab in a timely manner (within a week). It is considered a summative assessment.
The teacher will close the lesson with a discussion and Q and A session addressing any lingering misconceptions.
Summative Assessment
Students will complete the "Weight! What's the Mass" (attached) for the summative assessment. (Answer key is also attached.)
Students should be given a due date 3-4 days from when the lab is assigned.
The following scoring rubric should be used:
page 2 of 4 Hypothesis statement: the student used an If-then-because format (10 pts)
Questions 1-8: each question is worth 5 pts and the teacher may use his/her discretion for partial credit. (40 pts)
2 graphs will be graded, each graph will be worth (25 pts)
Student graphs need to include a Title, the variables must be labeled on the "X and Y" axis, and the Units of measurement are included. The teacher can use
discretion for partial credit.
A key is attached so the teacher will determine if the students have reached the learning objectives for the lesson.
Formative Assessment
Complete a Build a Bar Graph probe; students will be presented with a formative assessment probe on the LCD projector: "June and Mason went fishing"
Students will be provided 2 "sticky" notes where they will be instructed to sign their names on the back.
Students will read the assessment probe quietly and choose answer A, B, or C and write the answer on the front side of the sticky note.
2 large blank posters are labeled A, B, C at the bottom. One poster is labeled Part 1 and the other is labeled Part 2 (A, B, and C will create columns/a bar graph)
and the posters are hung in front of classroom. Students will be dismissed by rows/tables to place their sticky notes on the answer they chose. Students will be
instructed to place their sticky notes vertically to create a bar graph for the build a bar graph probe "June and Mason went fishing."
The teacher will be able to make quick assessments of their prior knowledge about mass and weight by noting the number of correct answers on the bar graph. If
there are a large number of incorrect answers, the teacher will remind students that mass measures the amount of matter in an object and weight measures the
gravitational force on an object.
The teacher will hand out "Weight! What's the Mass" lab (attached) to students, and the research question will be presented. Does an object's mass and weight
differ in and out of water?
Students will write a hypothesis statement using the "If, then, because" format to address the research question.
For example: If you measure an object's mass and weight in and out of water, then the mass of an object will not change, but the weight will decrease, because
the water pushes up on the object causing it to become buoyant.
The teacher may ask various students to read aloud their hypothesis statements and make comments such as, "Thanks for your response. Let's complete this lab
and see if your hypothesis is supported or not."
While the students are completing the "Weight! What's the Mass" lab, the teacher will be circulating around the lab stations asking formative questions such as:
How does a spring scale work?
What is the role of gravity on the object?
Why does the water level rise when an object is submerged in it?
Why does water cause the weight of an object to change?
Why is it so easy to carry a friend/relative in water as compared to out of water?
The teacher will listen to responses from students and respond with the correct answers:
A spring scale is a scientific tool that has a hook and a spring; when objects are hung from them the force of gravity is measured.
Gravity is the downward force applied to all objects with a mass.
When the object is submerged in water, the object forces the water to be displaced causing the water level to rise.
The water pushes up on the object causing the object to become more buoyant, thus decreasing the weight of the objects.
When an object is submerged in water its weight decreases making it easier to carry a friend in water compared to out of water.
**See attached MasonandJBfish document
Feedback to Students
While students are completing "Weight! What's the Mass" lab, the teacher will ask formative questions and may comment to students, "Are you surprised the weight
of the objects decreased?". Students might respond, "Now I understand why I can carry my friend in my pool." The teacher will respond with: "Awesome! I'm glad
you understand!"
When students complete the "Weight! What's the Mass" lab, The teacher will go back to the Build a Bar Graph probe in "June and Mason went fishing" and reveal
the correct answers.
The teacher will pull the sticky notes from students off the 'bar graph' one-by-one and will ask students to expound on their thought process as to how they came to
their conclusion.
Student answers may reveal misconceptions and impact future reteach moments in the classroom. For example: the teacher may ask students, "Does your mass or
weight change if you went planet hopping in our solar system?" Students should respond "that their mass would remain the same, while their weight would change
due to the different gravitational forces on different planets." If the student answers correctly the teacher will respond "Super!" If an incorrect answer is given the
teacher will respond by suggesting that the student "re-evaluate your answer by reviewing/studying your lab results."
ACCOMMODATIONS & RECOMMENDATIONS
Accommodations:
The teacher will accommodate students with special needs by pairing them up with a student who works well with students who struggle with labs and following
procedures.
The teacher will provide struggling students with more hands-on assistance while completing the lab.
Extensions:
The teacher may extend the lesson by having students calculate their weights on different planets by researching the planets' gravitational forces.
Suggested Technology: Computer for Presenter, Basic Calculators, LCD Projector
Special Materials Needed:
12 spring scales with Newton’s and grams/kg on opposite sides
12 tri-beam balances
12 large graduated cylinders (1000 ml)
12 10 gallon fish tanks or 12 large beakers (1000 ml) If the teacher does not have 12 fish tanks, the teacher can set up a single tank with a triple-beam balance
page 3 of 4 submerged and have students share the tank to measure the wet mass of the solid objects.
Various solid objects (toy cars, large bolts, magnets, bottles of sand, spring toys)
Water (1200 ml)
String (12 inches/lab group)
Further Recommendations:
If the teacher does not have 12 fish tanks, the teacher may set up one tank with a triple-beam balance submerged. The students will share the tank when
measuring the wet mass of the solid objects.
If the teacher does not have 12-1000 ml beakers, then 12-2 liter soda bottles with their top portions cut off will suffice.
SOURCE AND ACCESS INFORMATION
Name of Author/Source: Anonymously Submitted
Is this Resource freely Available? Yes
Access Privileges: Public
License: CPALMS License - no distribution - non commercial
Related Standards
Name
SC.8.P.8.2:
Description
Differentiate between weight and mass recognizing that weight is the amount of gravitational pull on an object and is
distinct from, though proportional to, mass.
page 4 of 4