In this Cyberchase activity, students first try to adjust a recipe to be 10 times larger. They examine the results to learn the procedure of adding a 0 to the multiplicand when multiplying by 10. To check their answers, students watch a video clip in which Bianca also has to increase the same recipe by 10. In the assessments, they are asked to adjust one recipe by multiplying by 10 and the other by dividing by 10.
Making Popcorn Balls QuickTime Video
Part I: Learning Activity
1. Read the following to your students: "Bianca and her friend are making popcorn balls for 40 kids at the school picnic. The recipe is given in the Plenty of Popcorn Ball handout. Due to a mistake, Bianca makes 10 times too much. Fill in the second column of the recipe to predict how much of each ingredient she uses."
2. Distribute the Plenty of Popcorn Balls handout .
3. Ask the students to complete the handout.
4. Read the following to your students, "You will now watch a video segment in which Bianca makes a mistake while making popcorn balls. Watch the video, and explain how the mistake was made. Also, check your answers with Bianca's."
5. Play the Making Popcorn Balls QuickTime Video .
6. Ask the students to share their methods for completing the handout. Be sure all students realize that multiplication by 10 is procedurally equivalent to adding a 0 to the original whole number. Also, discuss their methods for multiplying 1/2 by 10.
Part II: Assessment
Assessment: Level A (proficiency): Students use their knowledge of multiplying by 10 to increase a recipe to ten times the original amount.
Assessment: Level B (above proficiency): Students are asked to take a recipe and decrease it by ten times.