Click to access fully formatted lesson and materials:

Lesson excerpt:

NC Mathematics Standard:

NC.2.OA.2 Demonstrate fluency with addition and subtraction, within 20, using mental

strategies.

NC.2.NBT.5 Demonstrate fluency with addition and subtraction, within 100 by:

· Flexibly using strategies based on place value, properties of operations, and/or

the relationship between addition and subtraction.

· Comparing addition and subtraction strategies, and explaining why they work.

· Selecting an appropriate strategy in order to efficiently compute sums and

differences.

Standards for Mathematical Practice:

2. Reason abstractly and quantitatively.

6. Attend to precision.

7. Look for and make use of structure.

8. Look for and express regularity in repeated reasoning.

Student Outcomes:

I can add two numbers and use tens to find the sum.

Math Language:

What words or phrases do I expect students to talk about during this lesson?

tens, sum, strategy, teen numbers, make a ten

Materials:

• Game board for each pair of students.

• Deck of number cards for each pair of students, numbers 0-10, four of each number

• Transparent counters, two colors

Advance Preparation:

1. Copy the game boards.

2. Make the game cards.

Launch: 5-10 minutes

1. Introduce the game Snowballs or Play Ball. Ask students what they notice about the

board. Most will notice that all the circles have a ten and a number is added to it. Ask

students to share ways they would solve these problems. Highlight that there is a pattern

to adding a number to ten. Write the problems on the board and have students examine

the patterns.

2. 10 + 0 = 10 10 + 1 = 11 10 + 2 = 12 10 + 3 = 13 10 + 4 = 14 10 + 5 = 15

10 6 = 16 10 + 7 = 17 10 + 8 = 18 10 + 9 = 19 10 + 10 = 20

3. Explain that today we are going to play a game that helps us use our ten plus a number

facts to solve other problems.

4. Explain the rules of the game.

5. Play a few rounds with the class. As students solve the problems emphasize that we are

using our ten facts to solve “teen” problems. For example, if 5 + 7 is drawn, we can

think of 5 + 5 + 2 to solve the problem.

6. It may be helpful to record strategies so students have a visual model. For example,

8 + 3 could be shown as

8 + 3 =

1 7

7 + 3 = 10

10 + 1 = 11

Record several examples as cards are drawn.

7. The class may need to play an entire game together to understand the strategy used to

solve these problems. If you feel that the students need to play the entire game together,

this “launch” will be your entire lesson. Tomorrow’s lesson will be a review of the

game and using tens strategy, and then they will play the game with a partner.

Explore:

1. Pair students and have them play the game with a partner.

As the students are working, listen to their conversations. Look for strategies that will

generate discussions to help others move toward a deeper understanding of the

mathematical goal.

a. Are they discussing how to use tens to solve the problem?

b. Are they sharing their strategies with their partner?

c. Do some students automatically know some of these facts?

d. Are students using other related facts to solve problems? For example, 8 + 9

could be thought of as 8 + 8 + 1. During the share time, have students share other

ways they are solving the problems.

e. What vocabulary are they using as they discuss their strategies?

2. Observe how students organize and represent their thinking.

Discuss: 10 minutes

1. Bring the group back together and have selected students share their strategies for solving

the teen facts. As they share strategies relate the strategies to using ten facts to solve

harder facts.

2. Model on chart paper or the board how students are breaking apart the numbers. (See

example above.)

Additional Activities

1. Have students play these games multiple times to strengthen their understanding of using

tens (or other strategies) to solve harder addition problems. Playing a game once is not

enough to build this understanding. They need multiple experiences.

Evaluation of Student Understanding

Informal Evaluation: Observe the students as they play the game. Write notes about their

strategies.

Formal Evaluation/Exit Ticket: The activity sheet can be used as an exit ticket.

Meeting the Needs of the Range of Learners

Intervention: Check to see if students know their ten facts. If not, play making ten games such as

Tens Go Fish. (Directions follow on next page.)

Possible Misconceptions/Suggestions:

Possible Misconceptions

• Some students may not know the ten

facts and cannot use them to solve the

teen facts.

• Students break numbers in to smaller

parts but the parts are not helpful. For

example

8 + 3 =

6 2 This break apart

does not use the make a ten strategy.

Suggestions

• In a small group have students play

games for making tens or practice

the ten facts with flashcards.

• Practice breaking numbers apart to

make tens. After making sure the

students know their ten facts, give

students an equation such as 7 + 8.

Ask how to break the 7 apart (or 8)

to make a ten with the 8. Ask what

goes with 8 to make a 10. Do this

many times. Using Unifix cubes to

model the process may