Max folded two paper airplanes from the same paper and threw each one the same way. Only the wing width was different. Why does this make it a fair test?

Ravi's craft-stick bridge held five books and then snapped right in the middle. To improve his next prototype, what should he change?

Jen's paper parachute carried an egg down slowly on one drop. Her partner says one drop proves the design works. Why should they drop it several more times?

In a fair test, only one variable is changed and everything else is kept the same.

Two cups each held one ice cube. One cup was wrapped in a towel and put in the shade. The other sat bare in the sun. Why can this test not show whether the towel helped?

Using the same toy car and the same ramp height, Ben rolled the car down a smooth ramp and then down a ramp covered in cloth. The car rolled farther on the smooth ramp. What do the results show?

A bridge must hold ten books and use no more than 20 craft sticks. Design A holds twelve books with 30 sticks. Design B holds ten books with 18 sticks. Which design meets the criteria and the constraint?

In every trial, a paper airplane with one paper clip on its nose flew farther than the same plane with no clip. What is the best next change to test?

Engineers testing a prototype give a special name to the one thing they change on purpose. What is it called?

Sam's wrapped cup kept an ice cube solid for an hour, but water leaked out through a crack in the bottom. What do engineers call that crack?

Kim wants to find out whether a steeper ramp makes her toy car roll farther, so she raises one end of the ramp higher for her second try. What else should she change?

With the same glue and the same books, a bridge with craft sticks laid flat held 4, 5, and 4 books. A bridge with the sticks turned on edge held 9, 8, and 9 books. What do the results show?

A team builds a paper bridge to hold toy cars. What should they do first to find out if the bridge works well?

An engineering test should be fair. Which test is the fairest way to compare two parachute designs?

True or False: If a prototype fails a test, engineers can use what they learned to improve the design.

A windmill model spins too slowly in the wind. Which change is most likely to improve it?

A tower must stand at least 12 inches tall and use no more than 20 straws. Tower A stands 14 inches using 18 straws. Tower B stands 16 inches using 25 straws. Which tower meets the height goal and stays within the straw limit?

Students test a water filter and find the water is still cloudy. What evidence should they use to decide how to improve the filter?

True or False: Engineers usually improve designs by testing, changing, and testing again.

A toy car ramp is supposed to make a car travel far. The car only moves a short distance. Which data would best help improve the ramp?