Teacher Activity Guide: The Magic School Bus Discovers Flight

Ask, "What is air?" Discuss possibilities for the makeup of air.

Take a hand fan or a stiff sheet of cardboard and tell students to fan themselves. What do they feel on their faces?

Air is made up of molecules that are very small and far apart, but they still exist and have mass. Even though we can't see them, they exist and can push on us as with fans and the wind.

Show the deflated ball. Ask what is inside of it. Let students feel it and see if they can detect anything inside. Pump it half full. See if they can detect anything. Pump it full. See if they can squash it as flat as when there was no air in it. Why not? What keeps the sides apart? Think of all the cars on the highways. They are not riding on rubber, they are riding on air. The rubber just keeps the air in place.

Ask what happens when air is blown out of a hose. Is it high or low pressure? Since students can feel it pushing they may guess it is higher.

Grab a sheet of paper by one edge. Hold the edge up to your lips and blow across the top of it. The sheet should rise up. Since you are blowing across the top of the sheet what is making it rise?

Cut a three-inch piece of a small diameter straw. Using cardboard and tape, tape it at a right angle to the larger straw so that when you blow through the larger straw, you are blowing across the top of the smaller straw. Stick the bottom of the smaller straw into the cup of water. Blow hard through the larger straw. Water should be drawn up into the smaller straw, into the stream of air, and out. You have just created a siphon or spray gun.

The fast moving air has created a low-pressure area at the top of the small straw. The surrounding air is of higher pressure and pushes the water down in the cup and up the small straw. This is effective with thin poster paint and a big sheet of white paper.

Hook up the vacuum cleaner hose backwards so that it blows out. Tape the wand to a chair so that it points up. Turn the vacuum on and place an inflated beach ball in the stream of air. It should balance two or three feet up. Point to the fast-moving, low-pressure air. Point to the surrounding high-pressure air pushing the beach ball back and keeping it in place.

This was first theorized by Bernoulli, a Swiss mathematician.

Ask why a wing would make an airplane fly. Note the shape of a wing, usually curved on the top and flat on the bottom.

Pour water in a thin steady stream. Hold the drinking glass horizontally and touch it to the stream of water. The stream will attach itself to the glass and curve underneath the glass to shoot off sideways. This is a 'Coanda Effect'

Air behaves this same way with a wing. It hits the top of the wing, sticks, and is scooped or thrown down.

For years people had taught that air moved faster over the top of a wing causing lower pressure. Wind tunnel tests show that the air on top moves at the same speed as the air on the bottom and does not catch up. It is mismatched at the trailing edge. The air that is scooped or thrown down by the wing forces the airplane up in the air.

Airplanes fly more because of Newton's laws than Bernoulli's theorems. The air flowing over the top of the wing is bent down (action) and there is an upward force on the wing (reaction).

Roll the bottom corners of the bags and tape them so that an opening of 6 inches (125mm) is left. Flatten the dry cleaning bag on the floor and hold the bottom open. Turn the dryer on and fill the bag with hot air. Turn the dryer off and let go of the bag. What happens? (Be careful not to touch the bag with the dryer, it could melt and cause burns).

Record the amount of time the bag flies for each trial.

Clip a paper clip to the bottom of the bag. Does it still fly? Clip additional clips to the bag and see if it flies. Clip a clothespin to the bag and see if it flies.

Fill the kitchen trash bag with hot air. Does it fly?

Fill the lawn trash bag with hot air. Does it fly?

Hot air is less dense than cold air; therefore the same volume weighs less. Just like wood that is less dense than water floats, a balloon that is full of less dense air tries to 'float' in more dense cold air. It rises.

Small amounts of hot air will lift small weights but not large ones. Hot air balloons have wicker baskets and aluminum structures to keep weights low.

Mark a line on the floor. Have a student throw a sheet of paper as hard as he or she can. Measure the distance. Record the results. Make five trials. Have the student fold the sheet in half and repeat throwing five times. Have the student fold the sheet again into quarters and throw five times. Repeat until the sheet cannot be folded any longer. Graph the results with the number of folds on the horizontal axis and the distance thrown on the vertical axis.

What does the graph show? Since the weight of the paper remains the same, only its surface area changes. The drag on the folded paper is less and the distance traveled with the same thrust is more.

Tape a rock or weight to a piece of paper. Go outside. Leaving the paper flat throw it as far as you can.

Crumple the paper loosely around the rock and throw again.

Crumple the paper tightly around the rock and throw again. Which throw went farthest?

Attempt to throw the tightly crumpled paper only as far as the flat sheet went. Was less effort required? Discuss the amount of power and fuel needed to propel a streamlined airplane as opposed to an airplane with a lot of drag.

Make a paper airplane with a small notch in the bottom near the front. Reinforce the notch with tape. Tape the rubber band to the end of the yardstick. Fasten the yardstick to the back of a chair with clamps or tape so that it extends up at a 45-degree angle with the rubber band taped to the top of the high end. Hook the plane's notch into the free end of the rubber band and pull it back along the yardstick until taut.

Pull the airplane back one-inch and release. Record the distance flown. Repeat the trial four more times.

Pull the airplane back two inches and release. Record the distance flown. Repeat four more times.

Continue increasing distance of trials until you have reached the elastic limit of the rubber band.

Graph the results placing the distance pulled back on the horizontal axis and the distance the airplane flies on the vertical axis.

Discuss thrust and how it affects aircraft performance. Given the same aircraft, will a more thrust make it go farther? Faster?

Blow up a balloon and tie the end. Hold it in your hand and ask what will happen when you let go. Experiment by doing that several times.

Blow up a new balloon and do not tie it. Hold it by the end and ask what will happen when you let go. Even young students will correctly predict, based on past experiences, that the balloon will fly quickly around the room.

Balloons that have no outlet have forces that are in balance. The elasticity of the rubber is pushing in and the air is pushing out in equal amounts.

Balloons that have an outlet have 'unbalanced forces'. The rubber is pushing the air in, the air is pushing out all around the inside of the balloon but it is not pushing against rubber where there is an outlet. There are more forces pushing against the balloon opposite the outlet and it is forced to move in that direction.

Ask why the balloon does not move in a straight line. Discuss stabilizing fins on rockets.

If you put a short piece of straw in the opening of the balloon, would it straighten out the thrust? Would the balloon fly straight?