Paper helicopter experiment: a 40-minute variables lab, grades 3–5

1. Show how to build one: cut a strip, cut down the middle of the top third to make two wings, fold the wings in opposite directions, fold up the bottom and add one paper clip.
2. Drop it from the tape mark. Ask: "What do you notice? Why does it spin instead of falling straight down?" Collect ideas about air pushing on the wings.
3. Pose the question: "Does wing length change how long it takes to fall?" Pairs make three helicopters that are the same in every way except wing length: short, medium and long.
4. Agree on rules for a fair experiment as a class: same drop height, same release (wings level, let go without pushing), same number of paper clips. Say: "If we change two things at once, we won't know which one made the difference."
5. Each pair does three drops per helicopter, times them and records the times in a table drawn in a notebook or on a mini whiteboard. Ask: "Why three drops and not one?"
6. Pairs share their middle time for each wing length on a class chart. Look for a pattern together.
7. Each pair chooses a new variable to try next time (number of paper clips, paper type or wing shape) and writes a prediction.

Safety: drop from standing height only, never from chairs or desks, and keep scissors at the tables.

In my experience, the moment two groups disagree about a result is the best moment in the lesson. Send them back to try it again.

Differentiation: for newer students, pre-cut the strips and compare just two wing lengths. Advanced students can find the average of three drops and make a bar graph. English learners can use the frame "When I changed ___, the fall time ___." Students with motor needs can be the timer, the recorder or the dropper with a ready-made helicopter.

Quick check: "A group changed the wing length and the number of paper clips at the same time. What is the problem with their experiment?"

If you try it, reply with the variable your class picked next and what they found.