# Lesson 23

Two-Digit Numbers in Our World (optional)

### Lesson Purpose

The purpose of this lesson is for students to consider the magnitude of numbers to 99 by estimating and counting.

### Lesson Narrative

This lesson is optional because it does not address any new mathematical content standards. This lesson does provide students with an opportunity to apply precursor skills of mathematical modeling. In this lesson, students explore quantities of objects in order to develop a sense of how big various two-digit numbers are and to leverage their understanding of tens and ones to practice counting methods.

When students recognize the mathematical features of familiar real world objects and solve problems, they model with mathematics (MP4).

• Engagement
• MLR8

### Learning Goals

Teacher Facing

• Estimate, count, and represent collections of up to 99 objects.

### Student Facing

• Let's estimate how many objects are in a group.

### Required Materials

Materials to Gather

Materials to Copy

• Estimating Quantities Card Sort

### Required Preparation

Activity 1:

• Each group of 2 needs a bag of a collection of small objects.

Activity 2:

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

### Lesson Timeline

 Warm-up 10 min Activity 1 15 min Activity 2 20 min Lesson Synthesis 10 min

### Teacher Reflection Questions

Think about times when students were able to make connections to and build on the ideas of their peers during discussions today. What norms or routines allowed students to engage with other students’ ideas?

### Print Formatted Materials

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