Add Tens Video

The kids are out tonight, and they're all wearing costumes and collecting candy from friendly neighbors. Carol and Tim are so excited to see all of the children! Let’s help them count how many kids come knocking at their door.

Wow! Look at all of the costumes! Within the first hour, a group of 10 children visited Carol and Tim’s house, and then another 20 children came by. How many children came to Tim and Carol’s house within the first hour? We can use base ten blocks to help us add.

Here we have one group of ten and two groups of ten. Each of these base ten blocks represents the number ten, so this is 10+20. When we add these base ten blocks, we can think of adding 1 and 2. 1+2=3 groups of ten. We know that 3 groups of ten equals 30. Wow, that was so fast!

Because each of these base ten blocks is worth ten, we can check our answer by skip counting by tens. Ready? 10, 20, 30. That’s right! Carol and Tim had 30 neighborhood kids come to their door in the first hour.

I hear another knock. More costumes! In the second hour, a group of 20 children came by Tim and Carol’s house, and then another 30 children came by. Let’s help Tim and Carol find out how many children got some candy during that second hour.

These base ten blocks represent the number of children in the second hour of the night. Here we have two groups of ten and three groups of ten.

We know that 2+3=5. That means we also know that 2 tens plus 3 tens equals 5 tens.

If we think of these numbers in expanded form, 2 tens is 20, 3 tens is 30, and 5 tens is 50. That means 20+30=50. Carol and Tim had 50 visitors come to their door in the second hour of the night. It’s so easy to add these numbers when we think of them in groups of ten!

What’s that? Another knock! In the third hour of the night, 30 children came by Tim and Carol’s house, and then a smaller group of 10 children came by. Can you help Tim and Carol add these two numbers together using base ten blocks? Let’s try!

Remember, Tim and Carol had 30 and 10 visitors in the third hour of the costume party. What base ten blocks will you need to show 30+10?

That’s right! Three groups of ten makes 30 and one group of ten makes ten.

We know that 3+1=4. Those numbers help us understand that 3 tens plus 1 ten equals 4 tens.

If we think of these numbers in expanded form, 3 tens is 30, 1 ten is 10, and 4 tens is 40. That means 30+10=40. 40 children came to Tim and Carol’s house during the third hour.

Carol and Tim were thrilled to pass out candy to so many children! Thank you for helping them add the number of costumed kiddos using base ten blocks.