Bar Model — 1 + 3 = 4 — free printable diagram

What is 1 + 3?

This part-whole bar model shows 1 and 3 as the two parts of one whole. Adding the parts gives the whole, so 1 + 3 = 4.

First part

1

Second part

3

Whole

4

Addition

1 + 3 = 4

Subtraction

4 − 1 = 3

• A part-whole bar model shows the whole on one bar and the parts that make it on the bar underneath. Here the two parts are 1 and 3, and together they fill the whole bar of 4.
• The parts can be added in either order — swapping them does not change the whole: 1 + 3 = 3 + 1 = 4.
• Covering up one part turns the same picture into a subtraction: 4 − 1 = 3 and 4 − 3 = 1.
• That is the fact family for these three numbers — the model is the reason 1, 3 and 4 belong together, whichever way round you write them.