2 8 Making sense of addition and subtraction

2 -8 Making sense of addition and subtraction equations Today we will learn… • How to decide if both sides of an equation are equal • How to determine the value of an unknown number in an equation. Vocabulary • equation

equations We use different operations to solve equations. Name the 4 different operations: 1. Addition 2. Subtraction 3. Multiplication 4. Division With these operations we always use the …

What does equal mean? It means that one thing is the same as the other. Ex. 2 + 2 = 4

Sometimes there will be operations on both sides of the equals bar. Both sides added together equal the SAME number. 3+3=1+5 6 = 6

Are these equations equal? S E Y 10 - 4= 8 + 7 No 20 -10 = 1 + 9 S E Y no 10 + 5 = 20 - 5 7 + 11= 9 + 9 S S E E Y Y

Let’s try some with a missing numbers … 4+4=2+ Think … what is 4+4 8 =2+ 6 Just bring down the rest Now, think … 2 + what = 8 … This will give you what N equals. Think about your fact families. 2 8

You think you know what N = Let’s Check! 6 Where you see N, put the number you think N = 4+4=2+ 8 = 8

Let’s Try! 7+ = 12 + 2 = 14 7+ Now, think … 7 + what = 14 … This will give you what N equals. Think about your fact families. 7 14 7

You think you know what N = Let’s Check! 7 Where you see N, put the number you think N = 7+ 14 = 12 + 2 = 14

Remember, () first Let’s Try! 10 – (2 + 2) = 4 + 10 - 4 =4+ 6 =4+ 2 Now, think … 4 + what = 6 … This will give you what N equals. Think about your fact families. 6 4

You think you know what N = Let’s Check! 2 Where you see N, put the number you think N = 10 – (2 + 2) = 4 + 10 - 4 = 6 6

It’s your turn! Try a few independently!

Work with your partner A. 16 - = 7 B. + 5 = 12 C. 25 =19 +

Problem Solving Ana has 5 stamps. Ana's sister has n stamps. Together they have 16 stamps. Fill in the bar diagram and write an equation to model this problem. Then solve to find out how many stamps Ana’s sister has. Carefully read the problem. Underline the question. [Bracket] important words and numbers. Eliminate unnecessary information. Solve and check your work.