Labor Day may mean the end of summer break, but we can keep eating ice cream — and those ice cream trucks can keep rolling. Our friend Lisa B. asked, how many ice cream bars and popsicles does a truck sell in a day? Well, it depends where the truck goes. From our own experience, at a park a truck can unload 20-30 bars to one crowd. If the truck finds 10 good places like that, it can sell 200 to 300 bars that day. Remember, around 100 years ago we didn’t even have ice cream trucks. But in 1913 the electric freezer was invented, and in 1920 Harry Burt figured out how to coat ice cream in hardened dark chocolate. Suddenly people could sell ice cream from trucks. The driver pays less for the ice cream than he/she sells it for, so that’s how the driver makes money – and that’s where the math comes in.
Wee ones: Lots of ice cream bars look like rectangles. How many sides does a rectangle have? Is the floor of your room a rectangle?
Little kids: If a driver sells 4 ice cream sandwiches and 2 popsicles, how many ice cream treats is that? Bonus: If he sells an orange popsicle, then a lemon, then a cherry, then orange, lemon, cherry…what flavor is the 11th popsicle?
Big kids: If they keep selling orange, lemon, cherry, then orange to repeat, what flavor is the 25th popsicle? See if you can get it without counting up! Bonus: If the truck sells twice as many treats at the second stop as at the first, and sells 60 total, how many did it sell at each stop?
The sky’s the limit: If the driver buys each treat for $1, which way will make more money, selling 20 of them for $5 each or 30 of them for $4 each?
Wee ones: 4 sides.
Little kids: 6 treats. Bonus: Lemon.
Big kids: Orange, since it’s the first treat in a new set of 3. Bonus: 20 treats, then 40 treats.
The sky’s the limit: Selling 30 of them for $4. In the first way, selling them for $5 will make $4 extra on each, so 20 treats make $80. Selling for $4 will make only $3 on each, but 30 of those will make $90 total.
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.