The start of spring is all about baby animals. So our fan Audrey C. asked, how does a caterpillar turn into a butterfly? Well, the change from caterpillar to butterfly is kind of gross, but also really amazing. First, the caterpillar eats nonstop, and grows really fast for about 2 weeks. The bug ends up weighing 200 times as much by the end of it! Then it attaches itself to a tree branch and sheds its skin, under which there’s a hard skin called a “chrysalis.” Over 2 more weeks, most of the caterpillar’s body turns into goop, and re-forms itself into a butterfly. Finally the butterfly crawls out and pops open its wings. After 4 weeks of sitting with nothing to do, that butterfly must be excited to fly.
Wee ones: Like all insects, a butterfly has 6 legs. Is that more or fewer legs than you have?
Little kids: If the caterpillar eats for 2 weeks, how many days is that? Bonus: If that all starts on a Monday, what’s the 5th day the caterpillar pigs out?
Big kids: If you started eating nonstop today (March 20), what’s the date of your 14th day of eating? (Reminder if needed: March has 31 days.) Bonus: What if you weighed 200 times as much after that as you do now? What would you weigh? (Hint if needed: Multiplying by 200 is the same as multiplying by 2, then by 100.)
The sky’s the limit: If the whole caterpillar “metamorphosis” (growth and chrysalis) takes exactly 4 weeks, and a caterpillar partway through that has 6 times as much time left as it’s already done, how many days of metamorphosis has the little guy done?
Wee ones: The butterfly has more legs!
Little kids: 14 days. Bonus: That Friday.
Big kids: April 2. March 21 is the 2nd day, so March 31 is the 12th day, then we count forward 2 more. Bonus: Different for everyone…multiply your weight in pounds by 200.
The sky’s the limit: 4 days down, 24 days to go. Whatever part the caterpillar has lived already, it has 6 parts left of the same size, so there are 7 of those parts total…and 1/7 of 28 is 4 days.
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.