Cookies for Your Pet Grasshopper

Our fan Joey K. asked a great question: how fast could a grasshopper eat a cookie? Scientists aren’t sure how fast a grasshopper eats, but they do know that it can eat 16 times its own weight in 1 day! These bugs each weigh about half a gram, so the grasshopper could eat only 8 grams of cookie…to compare, 2 teaspoons of water weigh about 10 grams. Cookies come in all sizes, but if we go with the average of 16 grams, the bug would take 2 whole days to finish it off!

Wee ones: Most cookies are circles. Try to spot 4 circles in your room.

Little kids: If the grasshopper has taken 4 bites of cookie, what numbers are the next 3 bites? Bonus: If the grasshopper counts down the 8 grams of cookie while eating, what numbers does she say starting with 8?

Big kids: If the grasshopper starts eating 4 average cookies on a Monday, what’s the soonest day he can finish eating them? (Reminder: the grasshopper takes 2 days to eat 1 average cookie.) Bonus: If a giant grasshopper can eat 50 grams of cookie in a day, on what number cookie is his last bite?  (They’re all 16-gram cookies.)

The sky’s the limit: If a grasshopper eats 1/4 of a cookie, then the next day she eats 1/3 of what’s left, then on the 3rd day she eats 1/2 of what’s still left, what fraction of the total cookie is still there?

Answers:
Wee ones: Items might include a clock face, a plate, the edge of a cup, a button, or the flat end of a crayon.

Little kids: Bites 5, 6 and 7. Bonus: 8, 7, 6, 5, 4, 3, 2, 1!

Big kids: On the Tuesday a week later, since it takes 8 days. He’ll finish cookies on Weds, Fri and Sun.  Bonus: The 4th cookie, since 3 cookies will weigh 3 x 16 = 48 grams.

The sky’s the limit: 1/4 of the starting cookie. When the grasshopper eats 1/4 of the cookie, 3/4 are left. When she eats 1/3 of that, that’s like leaving 2/3 of it behind. And just as you multiply by 2 if you want 2 of them, you multiply by 2/3 if you want just 2/3 of it. So we do 3/4 x 2/3 = 1/2. The last day she eats 1/2 of what’s left, which is like leaving 1/2. So again we multiply: 1/2 x 1/2 = 1/4 left.

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