Lesson 4

The purpose of this Number Talk is to elicit strategies and understandings students have for multiplying within 100 with one factor larger than 10. These understandings help students develop fluency and will be helpful when students find factor pairs of numbers later in the lesson.

In this activity, students have an opportunity to look for and make use of structure (MP7) as they use a combination of products of smaller factors to find products of larger factors.

• 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.

• “How can knowing the value of the first two expressions help you find the value of the third expression?” (I can multiply in parts and add the smaller parts together to find a larger product.)

The purpose of this activity is for students to self-assess their own fluency with multiplication facts and practice the ones that are less familiar. Students are given a set of expressions. They sort them into categories of “know it right away,” “can find it quickly,” or “don’t know it yet.” Then, they identify products they don’t know (or don’t know well) yet, discuss strategies for finding those products, and practice using those strategies.

• Create a set of multiplication fluency cards from the blackline master for each group of 2.

• Groups of 1–2
• Give each group a set of fluency cards.
• “Take some time to sort the cards into one of the three groups.”
• 3–5 minutes: partner work time

• “Let’s share strategies for finding products we don’t know yet and practice with them.”
• “Choose 5 multiplication facts that you don’t know yet and record the expressions. These are the products you will practice finding.”
• 1 minute: independent work time
• “Now, share your list with your partner. Discuss some strategies you could use to find the products quickly. Afterwards, take some time to practice finding the products you chose.”
• 3–5 minutes partner work time

To support students in making connections between multiplication facts they know and those they are still working on, consider asking: “What do you notice about the numbers in the multiplication facts you are still working on?” or “Can you think of a related multiplication fact that might be helpful?”

• “What are some useful strategies for finding products you didn’t know yet?” (Think of a product I already know and use it to find the one I didn’t know yet. Imagine equal-size groups. Break the expressions into smaller numbers, find those products, and then add them.)

The purpose of this activity is for students to apply multiplication fluency within 100 to find factors of multiples within the range of 1–36. This game is Stage 1 of the center Find the Number. In this stage, students find all the factors for a given number.

• Groups of 2
• Give each group a copy of the blackline master and centimeter cubes.
• “We are going to play a game called Find the Number. Take a few minutes to read the directions.”
• 2 minutes: independent work time
• “What questions do you have about the game?”
• Consider playing a demonstration round or asking questions such as:
  • “If I covered the number 9, which factors would you cover?” (1, 3)
  • “What would your score be?” (4)
  • “What would my score be?” (9)

• 10–15 minutes: partner game time

• “What strategies were helpful for the game?” (Choose numbers with fewer factors to keep your opponent’s score low.)