Relating Addition and Subtraction

Relating Addition and Subtratction

What are we learning today?

​Today you will be…

​Learning about subtraction. What you know about addition can help you with subtraction, so we'll begin by looking for patterns in additinon and subtraction equations.

​Key Math Vocabulary in English and Spanish

​Addition	​Addition Equation	​Equals	​Minus	​Plus	​Subtraction	​Subtraction Equation
​suma	​ecuación de suma	​es igual	​menos	más	sustracción/ resta	​ecuación de resta

Watch as I write some addition equations with missing numbers.

1 + ____ = 10 9 + ____ = 10

2 + ____ = 10

3 + ____ = 10

4 + ____ = 10

5 + ____ = 10

6 + ____ = 10

7 + ____ = 10

8 + ____ = 10

Audio Response

What pattern did you notice in the last equation?

Open Audio Recorder

Draw

Tell me what other equations go together.

Now we'll subtract the numbers 1-9 from 10.

10- 9 = ____ 10- 2 = ____

10- 8 = ____ 10- 1 = ____

10- 7 = ____

10- 6 = ____

10- 5 = ____

10 - 4 = ____

10- 3 = ____

Audio Response

What patterns did you notice in the subtraction equations?

Open Audio Recorder

Draw

Tell me what other equations go together.

Let's Practice!

Here are two word problems that use the same numbers. One is an addition problem and the other is a subtraction problem.

Draw

Read the problem. I had $7, and then I saved $3 more. How much do I have now?

Draw

Read the problem. I had $10, but then I spent $3. How much do I have I left? Hint this is subtraction!

​What do these two equations have in common?

Draw

Read the question. I had $1, and then I saved $9 more. How much do I have now?

Draw

Read the question. I had $10, but then I spent $9. How much do I have left?

• Did you know you can use a pocket chart for subtraction?

• ​No we will subtract 3 from tens numbers such as 10.20, 30, and 40.

  • We know that

    10- 3 = 7. I can show that with my pocket chart.

​

​Pocket chart time!!!

Let's see how this can help us figure out:

20 - 3 =

30 - 3 =

40 - 3 =

​

​Let's use our pocket chart!

• Did you know?

" Knowing that 10-3 = 7 can help you subtract 3 from the other tens numbers. Let's see how in the next slide. " 

Draw

What is the same about these numbers?

Audio Response

Let's look at the tens digit of each answer and the tens digit in each starting number. Tell me what you notice!

Open Audio Recorder

Open Ended

How does knowing 10 - 3 = 7 help you subtract from other tens numbers?

From doing this lesson I noticed this pattern that shows that subtracting 3 from any number with 0 in the ones place gives you a number with 7 in the ones place.

• If you know 10 - 3 = 7, that helps you subtract!

​

I notice…

You can use page 3 as a pocket chart to help you solve your equations.

Quick Question:

How can the equation 10 - 5= 5 help you figure out the equation 50- 5?

​We will complete WorkSpace Page 2!