Common Core 3.NBT.2 ACOS 3.11and 2003 COS 3.2

Marilyn WhatleyLincoln Elementary

*A fact family is a set of related addition and subtraction number sentences that use the same numbers. You are practicing fact families every time you use XTRAMATH.com•Examples of fact families:3 + 4 = 7 7 – 4 = 3 4 + 3 = 7 7 – 3 = 4

2 + 8 = 10 10 – 8 = 2 8 + 2 = 10 10 – 2 = 8

Fluently means that I can get the correct answers when I add and subtract and that I can work without wasting my time.

I will make a plan as I solve a problem and use strategies that I know.

Watch and listen as I model how to use what I know (a strategy) to help me solve a subtraction problem.

(next 5 slides)

This part is the information I will need to solve the problem. I need to read it carefully. It is a good idea to read it twice and make a picture in my head.

This part is the question. It tells me what I need to

find an answer for.

N N N N N N N N N NN N N N N N N N N N N N N N N N N N N NN N N N N N N N N NN N N N N N N

N N N N N N N N N NN N N N N N N N N N N N N N N N N N N NN N N N N N N N N NN N N N N N N N N NN N N N N N N N N

Tom Brian

Brian delivered MORE. I need to find out HOW MANY MORE.

How many more papers did Brian deliver than Tom?

I know that HOW MANY MORE means that there is a difference in two numbers, so I think I need to subtract.

N N N N N N N N N NN N N N N N N N N N N N N N N N N N N NN N N N N N N N N NN N N N N N N N N NN N N N N N N N N

Tom

Brian

I need to subtract, or TAKE AWAY 47 from the largerNumber of 59.

N N N N N N N N N NN N N N N N N N N N N N N N N N N N N NN N N N N N N N N NN N N N N N N

The white Ns show thenumber of papers thatTom delivered. When I take that many away fromthe red papers of Brian, Isee a difference of 12 papers.

So 59 – 47 = 12

Now, I need to EXPLAIN how Igot my answer.

I subtracted the smaller number 47 fromthe larger number 59 and got a difference of 12 papers.

59 Brian’s papers - 47 Tom’s papers 12 difference

I can use words,

numbers, or both to

explain myanswer !

• Now, let’s work a problem together. Turn to the next page in your Math Journal.• Put today’s date at the top.• Put pencils down because first, we have to read the information .

Then we need to “picture the information”.

There are 16 third graders and 22 fourthgraders on the playground. How manymore fourth graders are on the playgroundthan third graders?What is the information?

Now picture that in your mind.

Cccccccccccccccc

3rd grader

s

Cccccccccccccccccccccc

4th

graders

There are 16 third graders and 22 fourthgraders on the playground. How manymore fourth graders are on the playground?

Cccccccccccccccc

3rd grader

s

Cccccccccccccccccccccc

4th

graders

There are 16 third graders and 22 fourthgraders on the playground. How manymore fourth graders are on the playground?

What is the question?

What should I do?

Cccccccccccccccc

3rd grader

s

CcccccCcccccCccccccccc

4thgraders

How many more fourth graders are on theplayground? I need to subtract to findthe difference.

22 fourth graders - 16 third graders

6

Work the problem in your journal.

Be sure to explain how you got your answer!

1 12

Examples of answers:

I subtracted the 16 third graders from the22 fourth graders and got a difference of 6more fourth grade students.

I took away 16 from 22 to find out therewere 6 more fourth graders than third graders.

22 fourth grade students- 16 third grade students 6 more fourth graders than third graders

• Now, it is YOUR turn to work witha partner to solve a problem.

• Remember to read the information.• Picture it in your mind.• Read the question.• Make a plan.• Both partners work the problem in their math journals.• Explain how you got your answer!

There are 15 fourth graders and 23 fifth graders in the gym. How many more fifth graders are in the gym than fourth graders?

Share students’ work usingELMO document camera.

More practice for students totry ON THEIR OWN on thenext slides.

There are 35 horses and 24 cows in the barn. How many more horses are there than cows?

Sara and her dad wentfishing. Sara caught 12 fish and her dad caught 21. How many more fish did dad catch than Sara?

First graders went on a field trip. 53 rode on the first bus and 57 rode on the second bus. How many fewer first graders rode the first bus than the second bus?

On Sunday, Mel texted her friends 47 times. On Monday, Mel texted her friends only 32 times because she had homework to do. How many fewer times did Meltext on Monday than Sunday?