Lesson 18

The purpose of this warm-up is to extend the verbal count sequence to 50 and to count on from a given number. As students count, point to the numbers posted so that students can follow along. If students struggle to count on, consider asking “What number comes after 4?” or providing a running start by counting “1, 2, 3…” and having students continue the count.

• “Let’s count to 50.”
• Count to 50.
• Repeat 1-2 times.

• “Let’s practice counting on. Start at 4 and count up to 20.”
• Count on from 4 to 20.
• Repeat 3–4 times starting with other numbers within 20.

• “If we wanted to count on from 5 to 20, what number would we say after 5? How do you know?” (6 because 6 is one more than 5 and comes after 5 when we count.)

The purpose of this activity is for students to tell a story problem that matches a given expression.

• Groups of 2
• “Think of one expression. You can think of an addition expression or a subtraction expression.”
• 1 minute: independent work time
• “Share your expression with your partner. Write the expression that your partner shares in the box.”
• 2 minutes: partner discussion

• “Think of a story problem that goes with the expression that you wrote in the box. Remember that a story problem should have a question at the end. You can draw pictures or write words and numbers in your workbook to help you remember what happens in your story problem.”
• 3 minutes: independent think time
• “Share your story problem with your partner. Does their story match their expression?”
• 3 minutes: partner discussion

• “In the next activity, we will share our story problems with the whole class.”

The purpose of this activity is for students to share story problems and figure out which expression matches a given story problem.

• Groups of 2
• “We’re going to do a gallery walk to hear the story problems that everyone created.”
• “As you walk around, fill in an expression for each story problem that you hear.”

• Invite half of the class to stand and share their story problems while the other half of the class walks around.
• 7 minutes: gallery walk
• Switch groups.
• 7 minutes: gallery walk

• Invite 1-2 students to share their story problems.
• “What expression goes with their story problem? How do you know?”
• “What in the story helped you figure out that you needed an addition/subtraction expression?”

The purpose of this activity is for students to choose from activities that offer practice with addition and subtraction story problems and expressions, as well as writing numbers. Students choose from any stage of previously introduced centers.

• Find the Value of Expressions
• Roll and Add
• Shake and Spill
• Number Race
• Math Stories

• Gather materials from: 
  • Find the Value of Expressions, Stage 1
  • Roll and Add, Stages 1 and 2
  • Shake and Spill, Stages 1-3
  • Number Race, Stage 1
  • Math Stories, Stages 1 and 2

• “Today we are going to choose from centers we have already learned.”
• Display the center choices in the student book.
• “Think about what you would like to do.”

• Invite students to work at the center of their choice. 
• 10 minutes: center work time

• “What centers are you looking forward to working with during the next unit? What kind of new centers do you hope to play?”