Source: Cyberchase: “A Battle of Equals”
Funding for the VITAL/Ready to Teach collection was secured through the United States Department of Education under the Ready to Teach Program.
In this video segment from Cyberchase, Bianca and Tracy are making popcorn balls for Tracy’s school picnic. They have to make enough for 40 kids. On their first try they find they have made way too much popcorn and not enough of the butter and marshmallow mixture. They realize they must adjust the recipe to make sure they have the right amount of each ingredient.
Download and ShareEveryday Math (2004)
Teacher Lesson Guide: pp. 86, 280-290, 298
Teacher Reference Manual: pp. 95, 272
Student Reference Book: pp. 18, 206
Here are some Frame, Focus and Follow-up suggestions for using this video in a math lesson.
What is Frame, Focus and Follow-up?
Frame: If you found a recipe in a cookbook for fried chicken, and it said that you needed 2 pounds of chicken to serve 4 people, what would you do if you wanted to serve 40 people at a picnic? How would you adjust the recipe? How much chicken would you need?
Focus: In this video segment, watch to see how Bianca makes the adjustment to the recipe once she has made too much popcorn. Note how she uses multiplication to adjust the amount of each ingredient needed.
Follow Up: Why did Bianca have to multiply different amounts of ingredients by 10? Is there an easy way to figure out the product when you multiply a number by 10? Describe it and give an example. If you had a recipe for a dozen candies that called for 3 tablespoons of vanilla, how much vanilla would you need to make 120 candies?
BIANCA: Today we’re making our favorite treat.
TRACY: Popcorn balls!! They’re for my school picnic this afternoon.
BIANCA: And they’re so delicious, because they feature two of my favorite foods: popcorn and marshmallows.
TRACY: But we can’t eat any, Bianca. We’ve got to make sure there are enough for the 40 kids.
BIANCA: Ok, 18 cups popcorn + 4 cups marshmallows + 1/2 cup butter = 40 popcorn balls
TRACY: One bag of marshmallows equals 4 cups. One stick of butter equals 1/2 cup.
BIANCA: First we’ll melt the butter and marshmallows. Okay. Now we do the popcorn.
TRACY: One bag equals 3 cups, so 6 bags equals 18 cups.
BIANCA: Tracy? Tracy! What’s wrong with this picture? There’s not nearly enough marshmallow-stuff to cover all this popcorn. I’ve gotta check the recipe again. Uh oh. I thought it meant 18 cups of unpopped popcorn. We were supposed to use 18 cups of popped popcorn. One cup of kernels makes 10 cups of popcorn. Uh no!
TRACY: So what do we do now?
BIANCA: Hmmm. We just need to adjust the recipe. Since we made 10 times more popcorn than the recipe calls for, we just need to multiply all the ingredients by 10. Instead of 18 cups of popcorn, we made 180. Instead of 4 cups of marshmallows, we need 40. And instead of 1/2 cup of butter, we need 10 times as much. Ten times a half is ten halves. That’s the same as ten divided by 2…or five cups of butter Ten times the popcorn, ten times the marshmallows, and ten times the butter means we’ll make ten times the amount of popcorn balls.
BIANCA: Wow! That means there will be tons leftover for us! Would you get out more butter and marshmallows?
TRACY: Sorry. We don’t have enough ingredients. We need to go back to the grocery store.
BIANCA: Yikes! We’d better hurry! The picnic is in two hours! Oh no. Where did I put my pocketbook? Got it.
TRACY: …36, 37, 38, 39, 40. That’s all I need. I gotta go. Sorry I can’t help make the rest.
BIANCA: That’s okay. Only 360 to go.
TRACY: Lucky you. Lots of your favorite treat leftover!
BIANCA: Favorite treat? Not any more. I hate popcorn.
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