Index card tower STEM challenge: a 45-minute middle school activity

1. Define (5 min): write the criteria and constraints on the board. Criteria: tallest tower, freestanding, holds the ball for 10 seconds. Constraints: 20 cards, 30 cm of tape, no taping the tower to the table.
2. Plan (5 min): no touching materials. Each team sketches two ideas and picks one. Ask: "Which shapes stand up best when you fold a card?" Many teams discover that folded triangles and tubes are stiffer than flat cards.
3. Build (12 min): set a visible timer.
4. Test (8 min): teams place the ball, count 10 seconds aloud and measure the height to the bottom of the ball in centimeters. Record every team's height and cards used on a class chart. A collapse is data too: note where it failed.
5. Improve (10 min): each team gets 5 more cards and one change. Retest and record the new height.
6. Debrief (5 min): compare the first and second heights. Which design changes helped most? What did the tallest towers have in common?

Math extension: calculate centimeters of height per card used, so a short, efficient tower can beat a tall, wasteful one. Teams can graph first-round versus second-round heights.

Differentiation: for students who need more support, show three pictures of base shapes (triangle, square, tube) before planning, and assign roles (builder, materials manager, recorder). For advanced students, add a cost: each card costs $2 and each 10 cm of tape $5, and the winning design has the best height per dollar. For English learners, post a word bank: criteria, constraint, base, load, stable, collapse. For students with fine-motor challenges, pre-cut tape strips and let them lead testing and measuring.

Quick check: exit ticket: "Name one criterion, one constraint, and one change you would make with five more minutes."

If you try it, post your class's tallest height and the design trick that got it there.