Lesson 6 Make a Ten and Make Sense of Equations

- Let’s add one-digit and two-digit numbers and make sense of equations.

Warm-up Number Talk: Add Within 20

Find the value of each expression mentally.

$8 + 2$
$8 + 5$
$9 + 8$
$7 + 6$

Activity 1 How Many to the Next Ten?

Problem 1

Find the number that makes each equation true.
Be ready to explain your thinking in a way that others will understand.

$45 +$ $= 50$
$38 +$ $= 40$
$63 +$ $= 70$
$24 +$ $= 30$
$42 +$ $= 50$
$57 +$ $= 60$
$71 +$ $= 80$
$89 +$ $= 90$

Problem 2

What did you notice about the unknown number in each equation?

Activity 2 Elena and Andre Add

Elena and Andre found the value of $34 + 9$ .

Elena started with $34 + 6 = 40$ .
What does Elena need to do next?
Show your thinking using drawings, numbers, or words.
Andre started with $9 + 1 = 10$ .
What does Andre need to do next?
Show your thinking with drawings, numbers, or words.
Find the value of $6 + 68$ . Show your thinking using drawings, numbers, or words.

Activity 3 Introduce Target Numbers: Add Ones

We are going to learn a new center called Target Numbers. Let’s play a round together. First, mix up your number cards.

Practice Problem

Problem 1

Find the value of each sum.
Show your thinking using drawings, numbers, or words.

$78 + 6$
$6 + 78$