Addition strategy using base ten blocks.

1. Base-Ten Block Addition Strategy

2. Question: Sally has 268 marbles. Jon has 157 marbles. How many marbles do they have altogether? Can you think of the equation for this problem? Answer: 268 + 157 = ?

3. 268 + 157 = ____ First, Let's draw a hundreds, tens, ones chart. Hundreds Tens Ones

4. Hundreds 268 + 157 Next, put the first number (268) onto the chart. Tens Ones

5. 268 + 157 Because we are adding, we put 157 MORE blocks onto the chart. Hundreds Tens Ones

6. 268 + 157 Now, we need to count up each column to see how many hundreds, tens, and ones there are. Hundreds Tens Ones 3 11 15

7. 268 + 157 There are 3 hundreds, 11 tens, 15 ones. Does that mean that 268 + 157 = 31115? Hundreds Tens Ones 3 11 15

8. 268 + 157 No! When there are 10 blocks in one column, we can make a trade. Hundreds Tens Ones 3 11 15

9. 268 + 157 Let's trade 10 ten blocks for 1 hundred block. **If you count 10 ten blocks it is the same as 1 hundred block** 10, 20, 30, 40, 50, 60, 70, 80, 90, 100 Hundreds Tens Ones 3 11 15

10. 268 + 157 Count 10 tens blocks, and move them into the hundreds column. Hundreds Tens Ones 3 11 15

11. 268 + 157 We can join the 10 ten blocks into 1 hundred block. Then write how many hundreds and tens are on the chart after the trade. Hundreds Tens Ones 3 11 15 4 1

12. 268 + 157 There are now 4 hundreds, and one ten. We have 15 ones, so we can trade 10 ones blocks for 1 tens block. Hundreds Tens Ones 4 1 15

13. 268 + 157 We can trade the 10 ones for 1 ten block. Count how many tens and ones are left. Write it in the column. Hundreds Tens Ones 4 1 15 2 5

14. 268 + 157 We have less than 10 blocks in each column, so we can’t make any more trades. That means we have our answer! 268 + 157 = Hundreds Tens Ones 4 2 5