To divide the shape in the image into three parts that can be rearranged into a square, I will first analyze the triangular arrangement of blocks. The shape consists of several squares arranged in a triangular grid pattern.

The number of squares corresponds to a sum of consecutive integers, specifically:

$1 + 2 + 3 + \dots + n = \frac{n(n+1)}{2}$

In this case, we need to determine the total number of squares and then proceed with how to divide the shape into three sections.

Let me calculate the number of squares in this triangular arrangement first.The triangular arrangement consists of 36 small squares. To create a perfect square from these, we need to find a way to divide the shape into 3 parts that can be rearranged into a square.

Since the total number of squares is 36, and $36$ is a perfect square, the side length of the square we aim to form is:

$\sqrt{36} = 6$

This suggests that the three parts should be divided in such a way that they can be rearranged to form a $6 \times 6$ square.

The next step involves finding logical cuts along the triangular shape to divide it into 3 parts that will fit together into a square. Would you like me to suggest a strategy for dividing the shape or provide an illustration of how it might be divided?