Those big Lego bricks look a little funny, don’t they? Well, it’s because they’re actually a giant cake. The bumps on top are upside-down cupcakes, hidden under icing! In the bottom right corner you can see the teeny real Lego that the cake copied. When we build bigger versions of objects, we have to go bigger in every direction. So if that cake is 10 times as wide as the Lego, it also needs to be 10 times as tall, and 10 times as deep back to front. So that cake can hold 10 times 10 times 10 bricks, or 1,000 of them! Toy dolls, cars and trucks do the opposite: they’re smaller versions of the real thing. But it’s even better if you can then eat what you made.
Wee ones: Which is smaller, the blue piece of cake or the yellow piece?
Little kids: How many Lego “bricks” do you see, including the toy bricks and the cake ones? Bonus: If you line up 12 Lego bricks along the bottom edge of the cake, what number brick do you put down next?
Big kids: If the yellow Lego cake were twice as wide, twice as deep and twice as tall as the blue cake, how many small blue Lego cakes would it take to fill the big one? (Don’t worry about the bumps, just the square parts.) Bonus: If the blue square cake can feed 2 people, and each bump feeds 1 more person, how many people can the whole yellow and blue cake feed? (Hint if needed: If the blue cake feeds 2, how many does the square part of the yellow cake feed?)
The sky’s the limit: What if the cake is 5 Lego bricks wide, 5 deep and 5 tall? How many Lego bricks would it take to fill it?
Wee ones: The blue cake is smaller.
Little kids: 4 bricks (2 big, 2 tiny). Bonus: 13.
Big kids: 8 blue cakes. Bonus: 22 people. The blue square feeds 2, the yellow square feeds 8 times as many (16), and then the 4 bumps feed 4 more.
The sky’s the limit: 125 pieces.
Laura Bilodeau Overdeck is founder and president of Bedtime Math Foundation. Her goal is to make math as playful for kids as it was for her when she was a child. Her mom had Laura baking before she could walk, and her dad had her using power tools at a very unsafe age, measuring lengths, widths and angles in the process. Armed with this early love of numbers, Laura went on to get a BA in astrophysics from Princeton University, and an MBA from the Wharton School of Business; she continues to star-gaze today. Laura’s other interests include her three lively children, chocolate, extreme vehicles, and Lego Mindstorms.