Question

thursday 2/5
what went wrong? - order of operations
directions: each problem below shows a students work. the student made a mistake. identify what went wrong and solve the problem correctly.
problem 1
$8 + 12 \div 3^2$
student work:
$8 + 12 \div 3^2$
$8 + 12 \div 9$
20
what went wrong?
solve it correctly:

Explanation:

Step1: Identify the student's error

The student added $8+12$ first, but division must be done before addition after evaluating the exponent, violating order of operations (PEMDAS/BODMAS).

Step2: Evaluate the exponent first

$3^2 = 9$, so the expression becomes $8 + 12 \div 9$

Step3: Perform division next

$12 \div 9 = \frac{4}{3}$

Step4: Perform final addition

$8 + \frac{4}{3} = \frac{24}{3} + \frac{4}{3} = \frac{28}{3}$ or $9\frac{1}{3}$

Answer:

What went wrong? The student added before doing the required division step after calculating the exponent, violating the order of operations.
Correct solution: $\frac{28}{3}$ (or $9\frac{1}{3}$)