# 3.MD.C.7b- Relate Area to Multiplication_Reed's Square

## 3.MD.C.7b- Relate Area to Multiplication- Flawed Reasoning

Evidence Statement 3.C.4-5 Distinguish correct explanation/reasoning from that which is flawed, and if there is a flaw in the argument, present corrected reasoning. (For example, some flawed student thinking is presented and the task is to correct and improve it.)

### Reed's Square

Reed thinks that the area of the square is 28 square inches because 4 x 7 = 28. This image is a square with one side labeled 7 inches.

## Part A

Explain why Reed’s thinking is incorrect.

## Part B

Find the correct area of the square using an equation.

## Scoring Rubric Part A

### Score 1

Student response includes the following element.

• Reasoning component = 1 points
• The student explains that Reed thought that since there were four sides he should multiply the 7 inches by 4. To find the area he should only multiply 2 side lengths.

### Score 0

Student response is incorrect or irrelevant.

## Scoring Rubric Part B

### Score 1

Computation component = 1 point

• The student provides the correct area and equation.
• 7 x 7 = 49, The area of the square is 49 square inches.

### Score 0

Student response is incorrect or irrelevant.