"Who can make the slowest marble run?" Rocket asks.
Raven reminds everyone, "It must roll all the way by itself."
Nova sets her timer. "I am ready to time each run."
Criteria say what success means. Constraints are the limits.
Gravity pulls the marble down.
A gentler slope and more friction slow it down.
Sometimes it takes many improvements.
◇ FAMILY SLOWEST MARBLE RUN
Each team gets cardboard, paper and tape. Build a run with chutes. Time the marble from top to cup. It must roll by itself, with no pushing. The longest time that reaches the cup wins.
For a grown-up
Keep marbles away from babies and toddlers. They are a choking danger. Help prop the cardboard on something steady. Ask: what did you change to slow it down?
Safety first
Marbles never go in mouths. Pick up every marble when you finish.
BUILD DAY CHECK
Read the question.
Tap your answer.
A marble run takes 9 seconds, but the marble falls off. Success?