States of Matter: Which Will Propel the Balloon?

Goals
1. Students will recognize the volume of space filled by the three states of matter.
2. Students will identify pressure and how it is exerted by the three states of matter.
3. Students will know that accelerating greater mass requires more pressure.
Key Concepts
- F=MA or A=M/F Accelerating greater mass requires greater force.
- Matter in gas will fill a greater volume than solid or liquid.
Vocabulary
- Pressure
- Force
- Matter

This activity can be taught by the classroom teacher or a science specialist. Students should be familiar with the process of guided inquiry, i.e. working with materials, solving a problem independently. Students should be familiar with group work, sharing tasks and materials. Students should be familiar with the process of journaling, i.e. analyzing, thinking, and communicating their questions and observations.

1. The Matter Model
Define a rectangular space in the classroom with string, tape or chairs. Leave an opening in one end of the rectangle for "gas" to escape. Students arrange themselves inside the rectangle in an array,e.g. four rows of six, standing close together almost touching. Students are atoms and they are moving slightly (fingers twitching). This is the SOLID STATE. Now students have to move their arms in a wavy fashion without touching one another. To do this they have to spread apart, take up more volume. This is the LIQUID STATE. Now students must move around the space with their whole bodies waving about without touching. If they need to, they can escape the rectangle. This is the GAS STATE.
2. The Balloon Rocket.
Materials
- Large balloon
- Drinking straw
- String or wire
- Tape
- Index cards
- Paper clips
- Marbles
- water
Students construct balloon rockets.
- Fasten one end of the string to a chair. A student will hold the other end.
- Tape straws to index cards on one end and tape two unbent paper clips (into an "S" shape) onto the bottom end.
- Slide the straw onto the string.
Students now attempt to propel the rocket by placing a solid (marble), liquid (water-50 ml) and a gas (air, from their lungs) into the balloon. The unbent paper clips on the bottom of the index card can be used to add weight to the rocket.

Students will analyze and communicate their observations.

Be prepared for a small amount of water mess. You can allow students to make private guesses as to what will happen.

Students must communicate why only a gas can propel the rocket.

Standards Match
Grade 4, Physical Science Matter, #2 4.2.1.2.1