Lesson 5

The purpose of this Number Talk is to elicit strategies and understandings students have for multiplying within 100 and to help students develop fluency.

When students use known multiplication facts to multiply larger numbers, 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.

• “How did you use multiplication facts that you already know to find some of the other products?” (I knew that \(3\times10\) is 30, so \(3\times13\) would be 3 groups of 10 and 3 groups of 3 which is 39. Once I knew \(3\times13\), I was able to find \(6\times13\) by doubling 39 which is 78.)

The purpose of this activity is for students to generate measurement data using rulers marked with half inches and quarter inches. Students go on a walk in nature, around the school, or on the playground to measure the length of items they chose. If time is limited, this activity could also be done in the classroom. 

Students may record and organize their data in the provided tables or on lined paper.

• Each group of 4 needs a ruler marked with half inches and quarter inches from a previous lesson.

• Groups of 4
• “Today we are going to take a walk around the school (or the playground, or the classroom) to measure the length of some objects.”
• “Talk to your group about some objects whose length we could measure on our walk.” (sticks, leaves, pine needles, plants)
• 1 minute: group discussion
• Share responses.
• Make sure each group has a ruler that shows halves and fourths of an inch (from an earlier lesson).
• If not using the table in the workbook, give students blank lined paper for recording measurements.

• “Discuss with your group what to measure on our walk. You’ll need to gather at least 10 length measurements.”
• “Later, each group will create a line plot with these measurements and display it on a poster.”
• 2 minutes: group work time
• Share responses.
• “Record and organize your measurements in the table (or on lined paper).”
• 20 minutes: whole-class walk around the school

• “Now that we have our measurements data, let’s make a line plot.”

In this activity, students create a line plot using the measurement data that they generated earlier and display their group’s line plot for all to see.

Encourage students to plan their line plot using the blank line in the activity statement before creating a poster version for display in a gallery walk. A template for a larger line plot is provided in the blackline master. Students can join the number lines on two copies of the blackline master to create a longer number line.

As students visit others’ data displays, they consider how the line plots are alike and how they are different, as well as why different scales might have been chosen for different objects measured.

• Groups of 4
• “Look at the data your group collected. What do you need to know to make a line plot that represents the data?” (The longest and shortest measurements. Whether the lengths are whole numbers or include halves and fourths of an inch.)
• 1 minute: group discussion
• Share responses.
• Give each group 2 copies of the blackline master, scissors, glue or tape, and tools for creating a visual display.

• “Work with your group to create a line plot that represents your data. You will share your line plot with the class later.”
• “You can use the blank number line on your page to plan your line plot before creating a final one to display.”
• Consider asking:
  • “How do you plan to make the scale for the line plot so that it can show all your measurements?”
  • “What information or labels could be included to help others understand your line plot?”
• Demonstrate how to join and tape (or glue) the 2 copies of the blackline master to make a large line plot.
• “After you complete your final line plot, tape (or glue) your line plot on a poster.”
• 12–15 minutes: group work time

• Ask students to display their posters.

MLR7 Compare and Connect

• “As you visit the posters with your group, think about how the line plots are alike and how they are different. Be prepared to share your observations.”
• 5 minute: gallery walk
• See lesson synthesis.