Cardboard Tube Marble Run

What you need

• Painter's tape, 1 roll
• Kid scissors, 1 pair (adult use for cutting tubes)
• Cardboard box, 1 (or a clear wall)
• Clear cups, 1
• Cardboard tubes, 6 to 10 toilet paper and paper towel tubes
• Pom-poms or ping pong balls, 2 or 3 (marbles for older kids only)

How to do it

Grown-up prep: Gather toilet paper and paper towel tubes, then slice each one in half lengthwise with scissors or a cutting tool to make open half-pipe ramps. Pick a clear patch of wall or the side of a big cardboard box. Marbles are a choking hazard, so use a pom-pom or ping pong ball if little ones are around.

1. A grown-up cuts each tube in half the long way to make ramps. A grown-up does this
2. Tape your first ramp high on the wall, tilted a little downhill.
3. Tape the next ramp below it, sloping the other way.
   Ask: Where do you think the ball will land when it falls off the first ramp?
4. Keep adding ramps in a zig-zag all the way down.
5. Set a cup at the very bottom to catch the ball.
6. Drop a pom-pom or ball in at the top and watch it zoom!
   Ask: Did it make it all the way? Where did it get stuck or fly off?
7. Fix any trouble spots by changing how steep the ramps are, then test again.
8. Race different balls down the track and compare.
9. Invite a friend to race, or build an even longer track!
   Ask: What twisty trick will you add to your next track?

Play it again

• Slow-poke track: make the slowest track that still lands the ball in the cup.
• Tunnel time: tape a whole uncut tube so the ball zooms through a tunnel.
• Two-way path: build a split so the ball can take either route to the cup.