Lesson 23
TwoDigit Numbers in Our World (optional)
Warmup: Estimation Exploration: Beans (10 minutes)
Narrative
The purpose of an Estimation Exploration is to practice the skill of estimating a reasonable answer based on experience and known information.
Launch
 Groups of 2
 Display the image.
 “The circled group shows 10 beans.”
 “What is an estimate that’s too high?” “Too low?” “About right?”
 1 minute: quiet think time
Activity
 “Discuss your thinking with your partner.”
 1 minute: partner discussion
 Record responses.
Student Facing
How many beans are there?
Record an estimate that is:
too low  about right  too high 

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Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 Select one “about right” estimate.
 “What are some ways we can think about this number using 10s and 1s?”
Activity 1: Count the Objects (15 minutes)
Narrative
The purpose of this activity is for students to have an opportunity to apply their place value understanding to estimate quantities of objects and accurately count familiar objects.
Required Materials
Materials to Gather
Required Preparation
 Each group of 2 needs a bag of a collection of small objects.
Launch
 Groups of 2
 Display for all to see approximately 15–25 beans or other small objects.
 “How many objects do you think are in this pile?”
 1 minute: partner discussion
 Share responses.
 “How could we find out exactly?” (Count them.)
Activity
 “How many objects are in 2 handfuls? Let's do an experiment.”
 Give each group a bag of objects.
 “Take turns and grab a handful. Estimate how many objects you both grabbed altogether. Then find out how many you have exactly.”
 “You will do this experiment three times.”
 5 minutes: partner work time
 Monitor for students who:
 count by ones
 group the objects into groups of 10 and then count the tens and ones
Student Facing
Record an estimate that is:
too low  about right  too high 

\(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\)  \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\)  \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\) 
Now find the exact number. ____________
Experiment 2: How many objects are in 2 handfuls?
Record an estimate that is:
too low  about right  too high 

\(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\)  \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\)  \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\) 
Now find the exact number. ____________
Experiment 3: How many objects are in 2 handfuls?
Record an estimate that is:
too low  about right  too high 

\(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\)  \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\)  \(\phantom{\hspace{2.5cm} \\ \hspace{2.5cm}}\) 
Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 Invite previously identified students to share.
 “Did your estimates get better with practice?”
 “How did organizing your objects help you to count?”
 “Imagine I have 72 objects. How many would you have if you have 10 fewer than I do? What if you had 10 more?”
 “If you had 72 objects, how could they be arranged in piles of 10 and ones? Are there any other ways?" (7 tens and 2 ones, 6 tens and 12 ones)
Activity 2: Quantities Card Sort (20 minutes)
Narrative
The purpose of this activity is for students to consider the number of objects in a group and represent numbers in as many ways as possible. Students should be encouraged to think about the number in terms of tens and ones. Students sort pictures based on the number of objects they estimate to be in each group.
Students should be encouraged to estimate quantities rather than try to count them. Some students may not have a reasonable estimate, but can be successful in this activity if they categorize the photograph based on whatever estimate they consider is “about right.”
Advances: Listening, Speaking
Supports accessibility for: Attention, Organization
Required Materials
Materials to Copy
 Estimating Quantities Card Sort
Required Preparation
 Create a set of cards from the blackline master for each group of 2.
Launch
 Groups of 2
 Give each group a set of cards.
Activity
 “There is a different picture on each card. Sort the cards based on the number of objects you think are in each picture.”
 8 minutes: partner work time
 As students work, consider asking:
 “What is an estimate that is too low, about right, and too high?”
Student Facing
 Estimate and sort the pictures based on the amount of items you see.
Sort into these groups. Less than 20
 20 to 50
 More than 50

Select 1 picture from each group.
Show the number of items you think are in the picture in as many ways as you can.Less than 20
20 to 50
More than 50
Student Response
For access, consult one of our IM Certified Partners.
Activity Synthesis
 Invite students to share what object they selected and its representation.
 Record responses.
 Select two estimates that have the same digit in the ones place.
 “How do we know which estimate is bigger?”
 Highlight the use of ones and tens.
Lesson Synthesis
Lesson Synthesis
“Today we made estimates and counted groups of objects. How did you use your understanding of tens and ones in twodigit numbers to help you with your work?”