It's A Weighty Matter

Summary

This activity will help students understand weight, mass and gravity.

Materials

• Ziploc bags (sandwich or quart size)
• One cup each of various items (marshmallows, gravel, rice, beans, cereal, etc.)
• Spring scale
• It's a Weighty Matter worksheet (pdf)
• Ruler

Additional Resources

Books

• Gravity, by Dan Greenberg (Newbridge Education Publishing, 1999, Item CA09660); ISBN 1582730245
• The Magic School Bus Plays Ball, by Joanna Cole: ISBN 0590922408
• Gravity: Simple Experiments for Young Scientists, by Larry White; ISBN 0761300899
• Bowled Over: The Case of the Gravity Goof-Up, by Chuck Harwood; ISBN 007007555
• Why Doesn't the Earth Fall Up?, by Vicki Cobb; ISBN 0525672532
• Which Way Is Up?, by Gail Kay Haines; ISBN 0689312857

Video

• Gravity is Attractive: What is Gravity? Produced by TMW Media Group

Laser disc

• Windows on Science, Primary Vol. 3, Force and Motion, Lessons 12 + 13

Background for Teachers

Earth's gravity pulls everything towards its center. Gravity gives objects their weight. The weight of an object is a measure of the pull of gravity on that object. Matter is anything that takes up space and has weight. Mass is the amount of matter something has. Weight is the pull of gravity on the mass. More mass means more weight, because there's more for gravity to pull on.

Intended Learning Outcomes

1. Use Science Process and Thinking Skills
2. Manifest Scientific Attitudes and Interests
3. Understand Science Concepts and Principles
4. Communicate Effectively Using Science Language and Reasoning

Instructional Procedures

Invitation to Learn
Race with Gravity (to be done with a partner)

Ask your partner to hold the ruler, hanging down (with 1 on the bottom and 12 on the top), just above your outstretched hand. When your partner releases the ruler, try to catch the ruler as quickly as you can. (By the time the message has traveled from your brain to your hand, gravity has already begun to pull the ruler down). Have a contest to see who in the class is the quickest to respond.

Instructional Procedures
Prior to the activity, place one cup of various objects into individual Ziploc bags. Paper punch a hole in the top corner of each Ziploc bag.

1. Estimate the order of the weights of the objects in the Ziploc bags from lightest to heaviest.
2. Measure the weight of each object using the spring scale.
3. Place the objects in the correct order from lightest to heaviest.
4. Graph the weights of the objects on It’s a Weighty Matter worksheets.

Extensions

Art

• Make a flip book illustrating the effects of gravity on an object.

Writing

• Write a story about a day without gravity.
• Pretend that you are Sir Isaac Newton and write a letter to a friend explaining your new discovery--gravity.

Family Connections
Race With Gravity
Have the students share this activity and the scientific principle involved at home with family.

A Homemade Scale

• Pencil
• Elastic
• Large paper clip
• Ruler
• Various objects to be weighed

1. Tape the pencil to a table, so half of the pencil is hanging over the edge.
2. Hang the rubber band on the pencil.
3. Open the paper clip so it looks like an "S."
4. Attach the small loop of the "S" to the rubber band.
5. Compare the weight of different objects by hanging them from the large loop of the "S" in the paper clip. Observe and measure the length of the rubber band with each object.

Critter Catch

• Toilet paper tube
• 18 inches of string
• 6" x 6" piece of aluminum foil
• Tape
• 2" square of paper

1. Cover the bottom end of the toilet paper tube with paper and tape securely.
2. Tape one end of a string onto the piece of aluminum foil.
3. Crumble the piece of aluminum foil into a ball (critter) around the string so the foil ball fits easily into the hole of the tube.
4. Attach the loose end of the string to the open end of the tube.
5. While holding onto the tube, swing the aluminum ball into the air. Try to catch the aluminum foil ball in the tube.
6. Bring the critter catchers to school and share designs with classmates.
7. Discuss what is happening. Gravity is pulling the aluminum foil ball down, toward the center of Earth.

Variation
Use a cup in place of the toilet paper tube and 2" square of paper.

Assessment Plan

• Did the student accurately read the spring scale?
• Did the student place the objects in the correct sequence from lightest to heaviest?
• Can the student accurately replicate the activity with different objects?