Heather Breaux
3rd. Grade
Division Unit
Lesson 6: Dividing by 3 and 4
Date:
Approximate Time: 60 minutes

Berks County Standards:
1. 2.1.3 Numbers, Number Systems and Number Relationships- C. Represent equivalent forms of the same number through the use of concrete objects, drawings, word names and symbols.
2. 2.1.3 Numbers, Number Systems and Number Relationships- L. Demonstrate knowledge of basic facts in four basic operations.
3. 2.2.3 Computation and Estimation- D. Demonstrate concept of division as repeated subtraction and as sharing.

NCTM Standards:
1. Number and Operations
7. Reasoning and Proof
8. Communication

Behavioral Objectives: Upon completion of this lesson, students will be able to...
1. Divide by 3 and 4
2. Know how to use multiplication to check their division facts

Materials/Technology Needs: 18 Enlarged cookies and 3 plates; Paddle Problem and What If problem in textbooks; dry erase boards and markers; tables 12 and 13 from p. 260; colored chalk; “Reteach 13.2” RW68; “Practice 13.2” PW68; “Memory” cards and baggies for groups of 3’s.

Anticipatory Set: Congratulate the students on a spectacular job of learning how to divide by 2 and 5 yesterday!! Begin the lesson by putting 18 enlarged cookies in a group and 3 paper plates on the board. Explain to the class that we need to separate the cookies into equal groups amongst the 3 plates so that Miss Sweigart, Miss Perritt, and I can each have a plate of cookies. We have to make sure that the plates have the same amount of cookies or we will have some angry teachers!! Ask what division sentence is being used and have a student come up and write it on the board. Ask, “How should we begin to solve this problem? Who can tell me how to do this by connecting what we learned yesterday to this problem?” (find a multiplication sentence because the two processes are inverse operations). Write 3 x ?= 18 (6). “So, how many cookies need to go on each plate so we can have happy teachers?” (6).

Procedure:
1. Introduce today’s topic as learning how to divide by 3 and 4, explaining that we are going to use the same procedures as yesterday, except just with new divisors. Turn the classes’ attention to the “Paddle Problem” on p. 260 of their textbooks. Have a volunteer read the problem and ask the class what division sentence is being used. Write the sentence on the board and have a student draw arrows and label each number in the sentence as the dividend, divisor, and quotient. Ask what the meaning of each number is in relation to the problem. Say, “If I was going to use a multiplication fact to help me solve this problem, what would I use?” ( 3 x ?= 24). Call on a student to fill in the question mark with 8. Say, “Because 3 x 8= 24, that tells us that 24 ÷ 3= 8 because of our knowledge about… (call on students for answers like fact families and inverse relationships).
Paddle Problem: The Traveler Scouts want to rent canoes. There are 24 people in the group. A canoe can hold 3 people. How many canoes should the group rent?
2. Have the students take out their dry erase boards and markers and solve the “What If” problem from p. 260 in the same fashion. Ask the students once again for the meaning of each number and have them write their answers on their boards. Have the students write the multiplication fact that helped them solve the division sentence and the answer to the question on their boards.
What If Problem: What if the group wants to rent rowboats instead? If each rowboat holds 4 people, how many rowboats should they rent?
3. Copy tables #12 and 13 from page. 261 onto the board and call on students to identify the number to fill in to make the number sentence true. Have the students explain their answer by writing the multiplication fact they used to check their work.
4. Pass out “Reteach 13.2” on p. 260. Read the top of the page as a class out loud and answer questions 1-6 together. For problems 7-23, have the students work in pairs, where they will individually solve on dry erase boards and compare each others work before coming upon an answer to write on their paper.
5. Split students into groups of threes, where each group will be given a baggie containing index cards with division sentences with missing quotients and index cards with multiplication facts on them. Each group will flip the cards upside-down and play the “Memory” game, where the object is to collect the most matches. Other students must double check all matches that are made, even if they are not their own, to be sure that it is indeed a match.
6. Hand out “Practice 13.2” PW68 on p. 260 for homework.

Accommodations Jessica will be seated at the front of the room so that she can see all problems on the board. I will provide her with enlarged worksheets to work with at her desk and for homework, as well as give her a larger version of the “Memory” game.

Closure: Write 18 ÷ 3; 12 ÷ 4; 28 ÷4; and 27÷3 on the left side of the board and 4 x 3; 3 x 9; 3 x 6; and 4 x 7 on the right side of the board. Call on students to draw a line using colored chalk to match the division sentences to the proper multiplication facts.

Key Questions:
1. “What process can we use to check our division facts?”
2. “Why can we use this process?”
3. “What two divisors did we work with a great deal today?”

Evaluation: I will be using “Reteach 13.2” problems 1-6, the table problems #12 and 13 from p. 261, and the students abilities to make matches during the “Memory” game as my formative assessment. The students’ homework assignment will be used as their summative assessment for the day.

Assignment: “Practice 13.2” PW68 on p. 260


Resources Used:
1. (2004). Harcourt Math Teacher Edition: Third Grade. Vol. 2.) Harcourt, Inc.

Frank D'Angelo, who submitted these articles, writes: [This] is an excellent unit submitted by a student in my Elementary Mathematics Methods Course.