When we add we count up. We have \(\displaystyle 4\) triangles in the first box, and then \(\displaystyle 3\) triangles in the second box. In total we have \(\displaystyle 7\) triangles. If you start at \(\displaystyle 4\) on a number line and count up \(\displaystyle 3\), you have \(\displaystyle 7\).

\(\displaystyle 4,5,6,7\)

When we add we count up. We have \(\displaystyle 2\) triangles in the first box, and then \(\displaystyle 2\) triangles in the second box. In total we have \(\displaystyle 4\) triangles. If you start at \(\displaystyle 2\) on a number line and count up \(\displaystyle 2\), you have \(\displaystyle 4\).

\(\displaystyle 2,3,4\)

When we add we count up. We have \(\displaystyle 2\) triangles in the first box, and then \(\displaystyle 4\) triangles in the second box. In total we have \(\displaystyle 6\) triangles. If you start at \(\displaystyle 2\) on a number line and count up \(\displaystyle 4\), you have \(\displaystyle 6\).

\(\displaystyle 2,3,4,5,6\)

We have \(\displaystyle 7\) triangles and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take them away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 6\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 7\) and count back \(\displaystyle 1\).

\(\displaystyle 7,6\)

We have \(\displaystyle 6\) triangles and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take them away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 5\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 6\) and count back \(\displaystyle 1\).

\(\displaystyle 6,5\)

We have \(\displaystyle 5\) triangles and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take them away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 4\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 5\) and count back \(\displaystyle 1\).

\(\displaystyle 5,4\)

We have \(\displaystyle 4\) triangles and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take them away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 3\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 4\) and count back \(\displaystyle 1\).

\(\displaystyle 4,3\)

We have \(\displaystyle 3\) triangles and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take them away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 2\) triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 3\) and count back \(\displaystyle 1\).

\(\displaystyle 3,2\)

We have \(\displaystyle 2\) triangles and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take them away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left. In this case we have \(\displaystyle 1\) triangle left. Subtraction is like counting backwards. We can start at \(\displaystyle 2\) and count back \(\displaystyle 1\).

\(\displaystyle 2,1\)

We have \(\displaystyle 1\) triangle and we want to subtract \(\displaystyle 1\) triangle, which means the same thing as take it away. We can cross off the \(\displaystyle 1\) triangle that we are subtracting, and count the number that we have left.In this case we have no triangles left. Subtraction is like counting backwards. We can start at \(\displaystyle 1\) and count back \(\displaystyle 1\).

\(\displaystyle 1,0\)