Peanut butter & jelly and order of operations
Students will discover the need for order of operations by giving step-by-step instructions for making a peanut butter and jelly sandwich.
A lesson plan for grade 3 Mathematics
- gain an understanding of the importance for order of operations.
- apply the order of operations to various mathematical problems.
Time required for lesson
- Loaf of bread
- Jar of Peanut Butter
- Jar of Jelly
- Plastic Knife
- Paper Plates
- Paper Towels
- Plastic Gloves
- Calculators for special-needs students
- Place the following problem on the board (or a similar problem):
6 + 3 x 8 / 4 - 5
- Ask each student to solve (there should be various answers as students find their own way to solve the problem).
- Discuss the possible reasons for the differing answers.
- Ask students to raise their hand if they know how to make a peanut butter and jelly sandwich (PB&J).
- Select one of those students to give you step-by-step directions for making a PB&J sandwich. Follow their directions to the letter!
Student- “Put the peanut butter on the bread.”
Teacher- Places the jar of peanut butter on the loaf of bread.
- Give another student the opportunity to give you directions. Again, follow their directions explicitly!
- Continue with this until you have made a PB&J sandwich or you feel that you have demonstrated the point of the activity.
- Discuss with the students the importance of established procedure for basic tasks, and point out that math is no different!
- Share the “established procedure” for order of operations through the mnemonic device “Please Excuse My Dear Aunt Sally.” Using the new “rules” re-write the problem from the pre-actvity on the board and ask students to solve it!
Give an example from your life where there is a specific order in which you must do something. Discuss why it is important that it be done in a certain order. Finally, tie in why it is important that students know the order of operations.
If you choose, you may want to give a sandwich to those who helped you “make” the PB&J sandwich. Of course, you need to ensure that no students have a food allergy to peanut butter or the type of jelly that is used.
North Carolina curriculum alignment
- Goal 1: Number and Operations - The learner will model, identify, and compute with whole numbers through 9,999.
- Objective 1.04: Use basic properties (identity, commutative, associative, order of operations) for addition, subtraction, multiplication, and division.