Vocabulary
What do the letters in PEMDAS stand for? (group them based off of 4 steps)
Parentheses
Exponent
Multiply and Divide
Add and Subtract
3 + 6 × 2
15
(5 + 1) × 3 – 4
14
Add 4 and 7, then multiply the result by 3.
3 × (4 + 7)
(4 + 7)×3
12 ÷ 3 × 2
12 ÷ 6
2
They started with Multiplication but M & D are left to right. So, Division should have been first
What does it mean to “evaluate” an expression?
To find its value / solve it using PEMDAS
20 ÷ (3 + 2)
4
24 ÷ 3 + 7 × 2
22
Start with 25, subtract the sum of 6 and 3.
25 – (6 + 3)
The student say (4 + 5 × 2) equals 18
(4 + 5 × 2)
(9 × 2)
(18)
18
They added before multiplying.
What is this an example of: 46
An Exponent
18 ÷ 3 + 7
13
30 – (2 × 4) + 6
28
Triple the difference between 18 and 4.
3 × (18 – 4)
20 – 6 + 3
20 - 9
11
Addition and Subtraction must go left to right, they should have started with 20 – 6
What are these called: { }
Braces
(12 – 6) × 4
24
(18 ÷ 3) × (4 – 1)
18
Add 10 and 8, multiply by 2, then subtract 6.
2 × (10 + 8) – 6
Student work: 30 ÷ 5 × 3 = 2
They Multiplied before Dividing
What is an “expression” (and how is it different from an equation)?
An expression does not have an equals sign; an equation does.
8 + 3²
17
50 ÷ (5 + 5) × 6
30
Add 12 and 4, then square the result
(12 + 4)²
6 + 3²
6 + 6
12
They incorrectly solved 3², it should equal 9. They multiplies 3 x 2 instead of 3 x 3