Children brainstorm the factors affecting the speed at which a space capsule reaches the surface of a planet or moon and suggest how engineers might deal with each factor. They create a plan for a capsule that will protect an egg that is dropped from a height. Once their designs are complete and approved, they build their capsule from the materials provided. If time allows, they test this model and refine it. Once all models are finalized, each capsule is dropped from a high point. The group records the results of each drop and discusses the strengths and weaknesses of each kind of design. The session ends by considering one or more thought questions.
What's the Point?
- All objects exert a gravitational force, and the greater an object's mass, the greater its gravitational force.
- As an object falls toward a planet or moon, gravity pulls it, causing it to accelerate until it impacts the surface.
- An object falling through an atmosphere hits air particles. These collisions interfere with its ability to accelerate, slowing the object. The collisions also produce friction, creating heat.
- Space capsules use a variety of methods to land safely on a surface, including parachutes, jet rockets, air-bag cushions, and wings.
For the group:
- Chalkboard, dry erase board, easel or large piece of paper, with chalk or markers (optional)
- 1 raw egg
- 1 hard-boiled egg (or plastic egg)
- Paper, pencils, markers, crayons
- Construction materials, such as: straws, cardboard, packing material, Styrofoam™, clean meat trays, egg cartons, string, rulers, paper towels, garbage bags, cotton, toothpicks, paper cups, sandwich bags, Ziploc® bags, cloth, etc.
- Drop cloth
- Ladder (or balcony)
- Paper towels
- Weighing scale (optional)
For each child or small group of children:
For the group:
For the facilitator:
1. With the children organized in a group, brainstorm the factors affecting the speed at which a space capsule reaches the surface of a planet or moon. List their suggestions on a board or chart. For each factor, have children suggest how engineers might deal with each one.
These factors include the mass of the capsule, the size and shape of the surface facing the ground, the density of the atmosphere, the gravitational pull of the planet or moon, and the initial speed of the spacecraft. Engineers could reduce the capsule's mass, maximize the area of the ground-facing side, use a parachute or wings to take advantage of an atmosphere, use jets and rockets to slow its descent, and have a spacecraft begin its descent at a slow speed.
2. Tell children that today, they will design a capsule to protect a raw egg as it is dropped onto a hard surface from a high place. Have them examine the materials for building their space capsules. Ask them what solutions come to mind for softening the egg's impact.
3. Have the children draw a face and flight suit on their raw eggs using colored markers. They can name their Egg-stronauts at this time. Place raw eggs back in egg carton.
Have the children carefully handle their raw eggs. Have them use markers to draw the face and body of their egg-stronauts on their eggs. Children can also name their eggstronauts. If you are concerned about children making a mess, you can have them wear smocks, not decorate their eggs, or use only hard-boiled eggs.
4. Have them design their capsules, labeling their drawings, naming their capsules, and listing their materials. Depending on their level, they can draw elevations, cutaways, or aerial views.
Individually or in teams, children should draw a plan of their capsule. Remind them that their design must be based on the available materials. Make sure they each do a drawing and label the parts and list the materials used.
5. After completing their plans and getting them approved, have children gather their materials and build a test capsule.
Give them a hard-boiled or plastic egg for this step. Save the raw eggs for the contest.
6. If time allows, have children make a test drop of their capsules when they have completed construction. Use hard-boiled or plastic eggs. After the test drop, have children redesign their capsules based on test results and update the plan, noting the revisions in their designs .
7. When the capsules are finalized, have children retrieve their Egg-stronauts from the egg carton and place them inside their capsules.
8. Put the eggs in the capsules and drop them from a tall ladder, balcony, or stairwell (could be done either inside or outside). During a drop, make sure children stay out of the drop zone.
Put the Egg-stronauts inside the capsules and drop them one at a time. On a piece of paper, have each team record its name, the kind of landing system used, and outcome of the landing.
9. On a board or chart paper, list the kinds of systems the group used (e.g., parachute, air bag, wing, helicopter, combination, ...) Record the number of capsules in each category and the success rate of each category. Ask the children to identify any patterns.
10. Consider discussing one or more of the following questions:
Why was it important to design your capsule on paper first? (Conserves materials, helps a team think through the problem and respond with well-considered solutions)
Why was it important to build and test a test capsule ? (One can rarely anticipate all the issues affecting a design)
What variables were there in designing your capsule? (Types of materials, weight, and strength of material, etc. )
What external factors may have affected the flight of your capsule? (wind, temperature, release technique)
How does the size and mass of the capsule affect how fast it goes and how great the impact is? (a larger mass falls faster, a larger volume increases air resistance)
What would happen if your capsule were launched from a greater height? (A greater impact might result with some designs. Other designs may have a softer impact due to their elements, such as a parachute, working better or for a longer period of time.)
How you could improve the design of your capsule? (Answers will vary)
What might happen to these capsules on a planet or moon with less gravity? (They would fall more slowly)
What might happen to these capsules on a planet or moon with less atmosphere? (Designs depending on air resistance would fall faster)
What might happen to these capsules on Venus where there is more air pressure and higher temperatures? (Designs depending on air resistance would fall more slowly)
Weigh the capsules before dropping them. The lightest one that protects its egg is the most efficient. Before they begin their designs, make sure to tell the children that weight is a criterion.
February 5, 2010