Building marble runs is a blast. Now imagine building a marble run that moves thousands of marbles at a time! A guy named Jelle Nikkers put together giant slides, zigzag ramps and tipping seesaws to make a giant machine that moves 11,000 marbles at a time. Check out the video to see the marbles do all kinds of tricks, and to hear the rushing river-like sound they make!

*Wee ones:* Which has *fewer* marbles, a seesaw holding 5 marbles or a seesaw holding 7 marbles?

*Little kids:* The first seesaw shown tips when it fills with 10 marbles. If 6 have rolled onto it so far, how many more are needed to tip it? *Bonus:* The machine holds 13,000 marbles total, with 11,000 on the move at once. How many marbles are sitting around waiting their turn?

*Big kids:* The whole marble run is 33 feet long and 4 feet wide! If you and your friends are all 5 feet tall, how many of you have to lie head to toe to stretch longer than the marble run? *Bonus:* If it fits inside a perfect rectangle, how far is it to walk all the way around it?

Answers:*Wee ones:* The one holding 5 marbles.

*Little kids:* 4 more marbles. *Bonus:* 2,000 marbles.

*Big kids:* 7 of you, since 6 of you will stretch only 30 feet. *Bonus:* 74 feet, since you have to walk the 33 twice and the 4 twice.