Lesson 11

The purpose of this Number Talk is to elicit strategies and understandings students have for finding related quotients, which will be helpful later in this lesson when students divide within 100.

When students use the relationship between multiplication and division and known division facts to find a division fact they don’t know, they look for and make use of structure (MP7).

• Display one expression.
• “Give me a signal when you have an answer and can explain how you got it.”
• 1 minute: quiet think time

• Record answers and strategy.
• Keep expressions and work displayed.
• Repeat with each expression.

• “There are lots of ways to divide 48. What are some other numbers that can be divided in many ways?” (24, because it can divided by 2 to get 12 or by 4 to get 6. 100, because it can be divided by 2, 4, 5, 10, 20, or 25.)

The purpose of this activity is for students to practice division within 100 by playing a game called Race to 1. The goal of the game is to repeatedly divide numbers until they reach one.

• Groups of 2
• “Take a minute to read the directions for Race to 1.”
• 1 minute: quiet think time
• “Let’s look at a sample game. Jada rolled a 3 on her first turn, then rolled 2 a few times afterwards. Talk with your partner about what her next move should be if she rolls 2 on her next turn.” (She should divide 4 or 6 by 2 because those moves get her really close to one.)
• 1 minute: partner discussion
• Share responses.
• Give each group a number cube.

• “Play Race to 1 with your partner.”
• 10–15 minutes: partner work time
• If students finish early, have them play again. Students can fill in the same numbers from the first game at the top of the columns of the second game or use the numbers 24, 36, 48, and 72 for a challenge.

• “How was having an efficient way to divide helpful as you played Race to 1?” (I had to decide which number I was going to divide, so it was helpful to be able to do it quickly. I had to divide a few times on each turn.)
• “What was a helpful strategy as you played Race to 1?” (I had to think about which number I could divide by the number I rolled. I divided the smallest number by the largest divisor to try to get to the quotient to be as small as possible so I could get to 1 first.)

The purpose of this activity is for students to practice dividing within 100. They do this by revisiting the Compare center introduced in a previous unit. (As was the case then, exclude cards with two-digit divisors from this activity.)

Students may compare expressions by finding the value of each or by reasoning based on the expressions (MP7). (For example, when comparing \(92\div4\) and \(84\div4\), they can recognize that \(92\div4\) is greater because it would be more groups of 4.) When students divide within 100, students should have an efficient method for finding the quotient, but do not need to know the quotient from memory.

• Gather materials from: 
  • Compare, Stage 4

• Groups of 2
• Give each group of 2 students a set of pre-cut cards.
• Play a round of Compare against the class.

• “Play Compare with your partner.”
• 10-12 minutes: partner work time

• “What were some division strategies that were helpful as you played your game?” (I used multiplication to help me divide. I used quotients that I knew to find quotients that I didn’t know.)