1. Fluently add and subtract within 1,000
3.NBT.2
Fluently add and subtract within 1,000

2. What does it mean to be fluent in addition and subtraction?
Fast
Accurate
Solving the problem with a variety of strategies
Understanding someone else's thinking
Proving why your answer is correct
Fining mistakes in other’s work

3. Would you add or subtract?
Look at the word problem below.
Will you need a variable?
Which operation will you use?
My friend sold 498 pieces of jewelry pieces were necklaces. The rest of the pieces were bracelets. How many bracelets did she sell?

4. At a construction site, 659 boards were ordered
At a construction site, 659 boards were ordered boards are needed for one project. How many boards will be left over for the second project?

5. Space
The average temperature on Mercury is 332° F. The average temperature on Earth is 57°F. What is the difference in temperatures?

6. How do you know?
543 – 246 = 297
Try to see if students can reason through this one?
For example, I know that 543 – 243 = 300
But there is 246 not just 243 so I need to take 3 more away from 300
So the answer is 297

7. Why did John solve the problem this way?
First solve the problem on your own in order to know the answer.
Then see how John solved the problem. Is he correct?
John: I added first. That equals 400 then I subtracted 3 to get an answer of 397.

8. Can you draw a picture to go with the explanation below?
I need to subtract 452 – 178
I started at 178 and counted up to see how far away I am from 452.
= 378
Then I added 2 to get to 380
Then I added 70 to get to 450 and then I just need to add 2 more. So my final answer is 274.
Is this correct?

9. Choose a problem to Add be prepared to explain your thinking
Have students choose an expression to solve mentally if students are ready, otherwise provide scratch paper or white boards.
Collect answers for the 3 addition problems. Rule out any incorrect answers. Have students prove it.
Do the same with the subtraction problems on the next slide

10. Choose a problem to Subtract be prepared to explain your thinking
456 – 322
302 – 178