# Lesson 4

One More and One Less (optional)

## Warm-up: How Many Do You See: One Less (10 minutes)

### Narrative

The purpose of this How Many Do You See is to allow students to use subitizing or grouping strategies to describe the images they see.

When students notice that one less is always the previous number in the count sequence they observe regularity in repeated reasoning (MP8).

### Launch

• Groups of 2
• “How many do you see? How do you see them?”
• Flash the image.
• 30 seconds: quiet think time

### Activity

• Display the image.
• 1 minute: partner discussion
• Record responses.
• Repeat for each image.

### Student Facing

How many do you see?
How do you see them?

### Activity Synthesis

• Display the last 2 images.
• “How did this image help you figure out how many dots there are in this image?” (I knew that there were 17 and 1 less is 16.)

## Activity 1: Count Out and Show One More or One Less (15 minutes)

### Narrative

The purpose of this activity is for students to count out a given number of objects and determine the new amount if one more is added or if one is taken away. Students may count the objects each time or may use their knowledge of the count sequence to determine the new amount (MP8).

MLR8 Discussion Supports. During partner work time, invite each partner to read each starting number and new number aloud. Listen for and clarify questions about adding and taking away.

### Required Materials

Materials to Gather

Materials to Copy

• Number Mat 1-20

### Required Preparation

• Each group of 2 needs 1 connecting cube and at least 20 two-color counters.

### Launch

• Groups of 2
• Give each group of students a connecting cube, a number mat, and two-color counters.
• “We are going to play a game called 1 More or 1 Less.”
• “First one partner will roll a cube onto the number mat and count out that number of counters.”
• Demonstrate rolling a cube onto the number mat and counting out the correct number of counters.
• “Now the other partner decides whether they want to take away one counter or add one counter.”
• Ask the class or invite a student to add 1 counter or take away 1 counter.
• “Now the first partner figures out how many counters there are now. Both partners use drawings or numbers to show what happened. How could I record what happened?” (You could write 15 and 14. You could draw 15 counters first and then cross one out because one was taken away.)
• Demonstrate recording based on student suggestions.

### Activity

• “Take turns playing with your partner.”
• 8 minutes: partner work time
• Monitor for students who know how many counters there are without counting when 1 is added or subtracted.

### Student Facing

Show how your partner changed the number.

Round 1:

Starting Number:

_______________

New Number:

_______________

Round 2:

Starting Number:

_______________

New Number:

_______________

Round 3:

Starting Number:

_______________

New Number:

_______________

Round 4:

Starting Number:

_______________

New Number:

_______________

### Activity Synthesis

• Display the number 14 and 14 counters.
• “Mai has the number 14. Her partner decided to add 1 more counter. How many counters will Mai have now? How do you know without counting all the counters?” (15. I know that 15 comes after 14 when we count. 15 is 1 more than 14.)

## Activity 2: Color One More or One Less (15 minutes)

### Narrative

The purpose of this activity is for students to practice using the count sequence to recognize 1 more or 1 less than a number. Students should have access to counters if needed to determine 1 more or 1 less than the given number.

An alternative version of the game is introduced in the lesson synthesis which students may wish to play.

Action and Expression: Develop Expression and Communication. Give students access to 10-frames to help them with counting in their game.
Supports accessibility for: Organization

### Required Materials

Materials to Gather

Materials to Copy

• One More, One Less Mat

### Required Preparation

• Each group of 2 needs the number mat, two-color counters, and the connecting cube from the previous activity.
• Each group 2 also needs crayons and a copy of the 1 more, 1 less mat.

### Launch

• Groups of 2
• “We are going to play another game with one more and one less. You will take turns rolling a connecting cube onto the number mat and the one more, one less mat.”
• “If my cube lands on 7 and 1 more, I need to color the number that is 1 more than 7 in my book. I’m going to color 8 because 8 is 1 more than 7.”
• “Once you’ve finished, record the starting number and the new number. I’m going to write 7 and 8. I rolled 7. 8 is 1 more than 7.”
• Give each group of students a number mat, a 1 more 1 less mat, a connecting cube, and access to counters and crayons.

### Activity

• “Take turns playing with your partner. You can make drawings or use counters if they help you.”
• 10 minutes: partner work time

### Student Facing

• Roll to choose a number and 1 more or 1 less.
• Color the number that is 1 more or 1 less than your number.
• Record the starting number and the new number.

Starting Number:

New Number:

Round 1:

_______________

_______________

Round 2:

_______________

_______________

Round 3:

_______________

_______________

Round 4:

_______________

_______________

### Activity Synthesis

• Display 17.
• “Clare and her partner rolled a 17 and 1 less. How can you figure out Clare’s new number?” (I just know that 16 is before 17. I know 6 is one less than 7 so 16 is one less than 17.)
• “Which numbers didn’t you color in? Choose one of the numbers and tell your partner one way that you could have covered that number.” (I could have covered 12 if we rolled 11 and 1 more.)

## Activity 3: Centers: Choice Time (15 minutes)

### Narrative

The purpose of this activity is for students to choose from activities that offer practice with number and shape concepts. Students choose from 5 centers introduced in previous units. Students can choose to work at any stage of the centers.
• Less, Same, More
• Math Fingers
• Tower Build
• Math Stories
• Which One
Students will continue to choose from these centers in upcoming lessons. Keep the materials from each center organized to use each day.

### Required Materials

Materials to Gather

### Required Preparation

• Gather materials from:
• Less, Same, More
• Math Fingers
• Tower Build
• Math Stories
• Which One

### Launch

• Groups of 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.”
• 30 seconds: quiet think time

### Activity

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

Choose a center.

Less, Same, More

Math Fingers

Tower Build

Math Stories

Which One

### Activity Synthesis

• “What makes working in centers fun for you?”

## Lesson Synthesis

### Lesson Synthesis

“Today we played games where we figured out one more and one less.”

Display the number mat and the student book page from the second activity.

“Kiran and Jada invented a new version of the game we played. Each time you roll a number, you color in both the number that is one more and the number that is one less. If they roll the number 7, which numbers would they color in? How do you know?” (They would color in 8 because when we count we say 6, 7, 8, so 8 is 1 more. They would also color in 6 because if you have 7 and take 1 away, you have 6.)

“Kiran and Jada colored in 9 and 11. What number did they roll? How do you know?” (They rolled 10. 11 is 1 more than 10 and 9 is 1 less than 10. If I show 10 fingers and put down 1 finger, there are 9 fingers still up.)