Take Away with Blocks: Your First Subtraction
You build a tall tower with 6 blocks. Then your little brother knocks off 2 blocks! How many are still standing? Let's count: 4 blocks are left. That is subtraction. Subtraction means we START with some, we TAKE AWAY some, and we count how many are LEFT.
What You'll Learn
- What "take away" means with real blocks - How to say a subtraction story, like 6 take away 2 - How to write it with the minus sign: 6 - 2 = 4 - How to check your answer by counting what is left
Start, Take Away, Left
Every subtraction has three parts. Put 5 blocks on the table. That is your START number: 5. Now slide 3 blocks away with your hand. You TOOK AWAY 3. Count the blocks still in front of you. 1, 2... there are 2 LEFT. So 5 take away 3 is 2.
When you take away blocks, slide them far to the side so you can see them. The blocks you slid away do NOT get counted. Only count the blocks that stayed!
The Minus Sign
Grown-ups write subtraction with a little line called the minus sign: it looks like -. "5 take away 3 is 2" is written 5 - 3 = 2. The first number is what you start with. The middle number is what you take away. The last number is what is left.
Zero Is Special
What if you take away ALL your blocks? You have 3 blocks and take away 3. Nothing is left! We write that as 3 - 3 = 0. The word for none is zero. What if you take away NOTHING? You have 3 blocks and take away 0. All 3 stay! So 3 - 0 = 3.
Match each block story to how many are LEFT.
Terms
Definitions
Drag terms onto their definitions, or click a term then click a definition to match.
You have 8 blocks. You take away 3. How many blocks are left?
Which block story matches 4 - 0 = 4?
Build-and-Break Subtraction
Get 10 blocks (or crayons, or crackers). 1) Build a tower of 7. 2) Knock off 2 and count what is left. 3) Draw the tower before and after on paper, and write the number sentence 7 - 2 = 5 under your pictures. 4) Do it two more times with different start numbers. Show a grown-up your three number sentences.
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