Candy Bar Challenge

Candy Bar Activity

• Divide the students into groups of 2 or 3. Give each group a candy bar.
• Explain that their task is to determine how many "breaks" it will take to break the candy bar into 12 equal pieces. One break of one piece of the candy bar will result in that one piece being divided into two pieces. Demonstrate a "break" by breaking the bar into two pieces. Then stack the two pieces together and break or cut the two pieces into four.
• At this point, have each student write in their journal the number of breaks they think it will take to break the bar into 12 equal pieces. This should be done without talking to their partner or group members.
• Working together with their partner or group, have the students discuss and then write their plan for solving the problem. They may revise their guess at this point.
• Once this is done, the students should implement the plan by opening the candy and breaking the candy and counting the number of breaks it takes to get 12 equal pieces.

Discussion of solutions

• Choose a group to present their plan to the class.
• How do the steps they used match what they wrote in their journal?

Introduction to the steps in the problem-solving process

• How do the steps they used relate to the “formal” steps of the problem solving process?
• Understand the problem – read or listen to the problem statement.
• Make a plan to solve the problem – use pictures, charts, graphs, systematic lists, objects, or act out the solution to help you devise a plan to solve the problem

In Computer Science we call this plan an algorithm.

• Carry out the plan – once the plan is conceived and understood, follow the plan. If you have planned well, this is the easy part.
• Review and reflect on how the problem was solved – Once the problem is solved, reflect on the plan that was used.
• Extend breaking the candy into N pieces
• Post chart of # pieces/# of breaks, including N and have students give you the # of breaks needed for each number of pieces.

Reflections on the candy bar problem: Ask the students to reflect on the candy bar problem. Why is this problem an important problem to solve for: a carpenter, a chef, a teacher?
 
Resources:
Polya, G. How to Solve It. 2nd. Princeton, NJ: Princeton University Press, 2004. candy bar problem suggested by Dr. Manuel Blum, Carnegie Mellon University.

More at https://csforallteachers.org/sites/default/files/legacy/unit_2_day_3.pdf