Question

Use the hundredth grids below to answer the questions. The first two hundredth grids show Sophia's work. The second two hundredth grids show Aiden's work.

This image shows Sophia's work. One whole 10-by-10 grid and 2 columns and 5 squares on a second grid are shaded blue. On the second grid, the remaining 5 squares in the third column, 3 more columns, and 5 more squares are shaded brown.

This image shows Aiden's work. One whole 10-by-10 grid and 2 columns and 5 squares on a second grid are shaded blue. On the second grid, 4 squares in the third column are shaded brown.

Part A

Which student correctly models the problem 1.25 + 0.4. Type your answer in the box.
Sophia

Part B
What is the correct answer for 1.25 + 0.4?

1.65

Part C
Explain the errors made by the incorrect student. Refer back to the models and use equations to support your explanation.

Answer 1

Aiden got the question wrong because he added four squares instead of four columns. Aiden confused 0.4 with 0.04, using 4 ones instead of 4 tens.

Im sorry if this is confusing i hope it helped :)