Using Models to Understand Addition

Question

Notice that the 2 ones and the 7 ones make 9 ____

And notice that the 2 tens and the 1 ten combine to make 3 tens, which is the same as _____

So now we have 3 tens and 9 ones, which is the same as 30 plus 9, and that gives us our sum of _____

Answer 1

When we notice that the 2 ones and the 7 ones make 9 ones, we can clearly see how they combine.

Next, when we look at the 2 tens and the 1 ten, they combine to make 3 tens, which is the same as 30.

So now, putting it all together, we have 3 tens (30) and 9 ones (9). This is the same as 30 plus 9, and that gives us our sum of 39.

So, your final statement would be: Notice that the 2 ones and the 7 ones make 9 ones. And notice that the 2 tens and the 1 ten combine to make 3 tens, which is the same as 30. So now we have 3 tens and 9 ones, which is the same as 30 plus 9, and that gives us our sum of 39.