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Lesson excerpt:

NC Mathematics Standard(s):

Add and subtract within 20.

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

Additional/Supporting Standards:

Work with equal groups of objects to gain foundations for multiplication.

NC.2. OA.3 Determine whether a group of objects, within 20, has an odd or even number of members by:

·         Pairing objects, then counting them by 2s.

·         Determine whether objects can be placed into equal groups.

·         Writing an equation to express an even number as a sum of two equal addends.

Standards for Mathematical Practice:

1.   Make sense of problems and persevere in solving them.

2.   Reason abstractly and quantitatively.

5.   Use appropriate tools strategically.

6.   Attend to precision.

Student Outcomes:

• I can use mental strategies (e.g., count on, make a ten) to add or subtract numbers within 20 with ease.

• I can begin to recall doubles from memory.

Materials:

• Chart Paper

• Fluency Fun Game board for each player

·         Deck of number cards (1-10; 4 sets per pair)

·         Counters to cover numbers on game boards

Advance Preparation:

Thinking:

In first grade students add and subtract within 20, demonstrating fluency for addition and subtraction within 10. Use strategies such as counting on; making ten (e.g., 8 + 6 = 8 + 2 + 4 = 10 + 4 = 14); decomposing a number leading to a ten (e.g., 13 – 4= 13 – 3 – 1 = 10 – 1 = 9); using the relationship between addition and subtraction (e.g., knowing that 8 + 4 = 12, one knows 12 – 8 = 4); and creating equivalent but easier or known sums (e.g., adding 6 + 7 by creating the known equivalent 6 + 6 + 1 = 12 + 1 = 13). In this task students are expanding on this knowledge of 10 to 20.

Materials:

Prepare game boards for each student and a set of cards for each set of partners.

Directions:

1.      The teacher starts the task by giving the students a doubles problem such as 5+5. Then asks students what would be the strategy they used to solve this problem. For example I know that 5+5= 10, I have 5 fingers on my hand so 2 hands equal 10 fingers, when I count by 5’s 10 comes after 5. Charting responses as the students say them. Repeat this process with other doubles.

2.      Demonstrate the game Fluency Fun with the teacher playing against the class. To play the game students have a game board and place the number cards face down. The teacher draws 2 cards and adds the numbers on the cards together, placing a marker on the teacher’s game board on the sum. Then the teacher chooses a student to pick a 2 cards and place the sum of those numbers on the class game board. The game continues until the players cannot cover any more spaces on the game board.

3.      After the game is completed ask students to add any strategies they used while playing the game to the chart.

4.      Divide the class into pairs.

5.      While the students are playing, the teacher walks around room and observes and asks students if they are using any of the strategies on the chart.

6.      Teacher brings students back together and discusses the chart and adds any strategies if needed.

Questions to Pose:                                            

During:

How did you solve the problem?

How are you using any of the strategies from the chart?

How does it help you to visualize the doubles?

After:

How do the strategies we discussed help with knowing your math facts?

Draw a picture showing a partner what you have learned?

Possible Misconceptions/Suggestions:

Special Notes:

It is important to remember that just because students have memorized the basic facts does not ensure that they see how numbers relate to each other. Students understand the meaning of the facts. This understanding plays a major role in their number sense and mental computation.

This standard needs to be addressed at multiple times throughout the school year. Fluency with addition and subtraction is not something that can be taught in a couple of lessons it needs to be embedded in lessons throughout the year.

Solutions: N/A

Adapted from Partners for Mathematics Learning 2009

Fluency Fun

Concepts:

• Develop fluency with addition within 20.

• Explore patterns in odd and even numbers

• Practice number combinations

Materials

• Game board for each player

• Deck of number cards (1-10; four sets per pair)

• Counters to cover numbers on game boards

Rules

1.           Each player has a game board.

2.           Place the number cards face down.

3.           Player One draws 2 cards from the deck. Cover the sum of the cards with a counter.

4.           Player Two draws next.

5.           Play continues until the players cannot cover any more spaces on the game board.

6.           This game can be played so that there is no winner. The children just continue covering numbers until there are none to cover. The game can have a winner. The person with the most spaces covered is the winner.