3.NBT.2

Fluently add and subtract within 1,000

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

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. 287 pieces were necklaces. The rest of the pieces were bracelets. How many bracelets did she sell?

At a construction site, 659 boards were ordered. 390 boards are

needed for one project. How many boards will be left over for the

second project?

Space

The average temperature on

Mercury is 332° F. The average temperature

on Earth is 57°F. What is the difference

in temperatures?

How do you know?

• 543 – 246 = 297

Why did John solve the problem this way?

• First solve the problem on your own in order to know the answer.

225 + 178 • Then see how John solved the problem. Is he

correct?

• John: I added 225 + 175 first. That equals 400 then I subtracted 3 to get an answer of 397.

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.

• 178 + 200 = 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?

Choose a problem to Add be prepared to explain your thinking

• 328 + 678

• 567 + 123

• 789 + 88

Choose a problem to Subtract be prepared to explain your thinking

• 456 – 322

• 302 – 178

• 999 - 555