2 3 Using Mental Math to Add Today

2 -3: Using Mental Math to Add Today we will learn… How to solve problems by adding with Mental Math Vocabulary • Sum • Addend

Vocabulary Review 2+5=7 ? ? • The addends are all of the numbers that you are adding together. • The sum is the answer to an addition problem. • Which box shows the addends, and which shows the sum?

Talk with your partner Name a time when you had to add in your head. Today we will learn a mental math strategy to help you do this.

Mental Math by breaking apart 1 addend 25 + 14 = ? 1. Break Apart the 14 into the tens and ones (expanded form): • 14= 10 + 4 2. Add 10 to 25 • 10+25=35 3. Add 4 to 35 • 35 + 4 = 39 So 25 + 14 = 39

Work with your partner Use the break apart 1 addend strategy to solve these 2 problems on your whiteboard: A. 25 + 12 B. 38 + 26

Mental Math by breaking apart both addends 25 + 14 = ? 1. Break Apart both addends (expanded form): • 14= 10 + 4 25 = 20 + 5 2. Add the tens and ones separately • 10+20=30 4+5=9 3. Add the 2 sums together. • 30 + 9 = 39 So 25 + 14 = 39

Work with your partner Use the break apart both addends strategy to solve these 2 problems on your whiteboard: A. 72 + 16 B. 53 + 39

Problem Solving David’s Dad spent $27 on tickets to the baseball game. He also spent $24 on food. About how much did he spend in all? Complete the Bar Diagram and write a number sentence to solve. Carefully read the problem. Underline the question. [Bracket] important words and numbers. Eliminate unnecessary information. Solve and check your work.