Order of Operations — PEMDAS

Order matters. 3+4×2 is 11, not 14. The rule is universal convention. The calculator is the control. Indirect aim: algebraic expressions, preparation for programming, disciplined computation.

• Framework: Montessori
• Unit: Mathematics
• Learning area: Operations
• Level: Ages 7-9

Objectives

• Apply order of operations: Parentheses, Exponents, Mult/Div, Add/Sub
• Compute multi-operation expressions correctly
• Understand why order matters
• Use calculator to verify

Materials

• PEMDAS chart
• Problem slips
• Calculator
• Worked examples

Instructions

1. Rule: PEMDAS (Please Excuse My Dear Aunt Sally). 2. Parentheses first: 2×(3+4) = 2×7 = 14. 3. Exponents next: 2³+1 = 9. 4. Mult/Div left to right. 5. Add/Sub left to right. 6. Compute 3+4×2 = 3+8 = 11 (NOT (3+4)×2=14). 7. Compute 24÷(3+1)×2 = 24÷4×2 = 6×2 = 12. 8. Verify with calculator.

Educator tip

Left-to-right for same-priority operations matters. 12÷3×2 = 4×2 = 8, not 12÷6=2.

Assessment

Observe correct order application and verification.

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• Statistics — Mean, Median, Mode
• Negative Numbers — Full Operations
• Linear Graphs — Slope and y-Intercept
• Mental Math — Shortcuts and Tricks
• Geometric Proofs — Simple Theorems
• Exponents — Laws and Applications
• Data Collection and Analysis Project