Choose the sheet for the learner's age. Each prints on a single page. Build the project first, then fill it in together.
Ages 5-7: Draw & tell
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Cup Flyers · Ages 5-7
My Cup Flyer
Launch your flyer and watch where it goes.
1. Draw your cup flyer with its rubber band.
2. When you let go, did the cups go up or down?
◯ Up◯ Down
3. Draw the path the cups flew. Use a curvy line.
4. Were the cups spinning as they flew?
◯ Yes◯ No
5. What made the cups spin?
Ages 8-10: Predict, test & record
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Cup Flyers · Ages 8-10
Spin and Curve Test
Predict what your flyer will do, then test it and record what happens.
1. Predict: when you launch your flyer with the band coming off the bottom, what will it do?
◯ Fall like a thrown ball◯ Fly straight◯ Curve up◯ Curve down
2. Launch 4 times. Change one thing each time (number of wraps, which way you wind, cups lying down or standing up).
Try
What I changed
Which way it curved
3. Draw your flyer from the side. Add an arrow showing which way it spins when it climbs.
4. When you wound the band the other way, the flyer curved:
◯ Up◯ Down◯ Sideways
5. What did you find out?
6. Why do you think the spinning cups climb instead of falling?
Ages 11-14: Explain & design your own test
Name: ______________________Date: ____________
Homemade Science with Bruce Yeany · Cup Flyers · Ages 11-14
Explaining the Magnus Effect
Use what you saw and the idea of the Magnus effect to explain your flyer.
1. Use the term Magnus effect to explain why the flyer climbs.
2. With backspin (top of the cups moving back toward you), the push from the air points:
◯ Up◯ Down◯ Forward◯ Sideways
3. In your tests, name one variable you changed, one thing you watched or measured, and two things you kept the same.
4. Plan a fair test of one variable (for example, number of wraps). Change only that one thing.
What I changed
What I kept the same
Result (height, distance or curve)
5. A spinning cup held still in the air gets no push. Why must the flyer also move forward for the Magnus effect to work?
6. Where else does spin make a ball curve, rise or dip?
Answer guide for grown-ups
Homemade Science with Bruce Yeany · Cup Flyers · Answer guide
Answer guide
Ages 5-7: My Cup Flyer
Open answer: look for effort and careful observation.
Up (with the band coming off the bottom, the cups swoop upward).
Look for a line that rises or curves upward instead of dropping straight down.
Yes
The rubber band unwinding (it spins the cups as it pulls them).
Ages 8-10: Spin and Curve Test
Curve up.
Open answer: look for effort and careful observation.
The arrow should show backspin: the top of the cups turning back toward the launcher.
Down
The way the cups spin decides which way they curve: backspin curves up, the other way curves down, cups on end curve sideways.
The spinning cups throw air downward behind them, so the air pushes the cups up (the Magnus effect). The cups are light, so this push can beat gravity.
Ages 11-14: Explaining the Magnus Effect
The rubber band gives the cups backspin. As the spinning cups move through the air they drag air around and throw it downward; the air pushes back, giving an upward force (the Magnus effect) that can be bigger than the light cups' weight.
Up
Changed: e.g. number of wraps, spin direction, cup size or cup orientation. Measured/watched: height, distance or which way it curved. Kept the same: e.g. cup type, how far the band is stretched, launch height, number of rubber bands.
Open answer: look for effort and careful observation.
The push comes from air flowing past the spinning surface being thrown to one side. If the cup is not moving through the air, there is no flow past it to deflect, so there is no sideways push.
Examples: backspin keeps golf balls and basketball shots up longer, topspin makes tennis balls dip, sideways spin makes a curveball or a soccer ball curve.