# Lesson 1

Sums I Know

## Warm-up: Notice and Wonder: Addition Table (10 minutes)

### Narrative

The purpose of this warm-up is to elicit the idea that there are many sums within 10, and students may already know many of these sums. This will be useful when students identify sums they know and don’t know in a later activity.

### Launch

• Groups of 2
• Display the image.
• “What do you notice? What do you wonder?”
• 1 minute: quiet think time

### Activity

• 1 minute: partner discussion
• Share and record responses.

### Student Facing

What do you notice?
What do you wonder?

### Activity Synthesis

• “This table shows all the sums that you need to know by the end of the year. As you noticed, there are some you already know.”
• “Tell your partner three sums you know.”

## Activity 1: My Favorite Sum (15 minutes)

### Narrative

The purpose of this activity is for students to explore sums within 10. Students pick their favorite sum as an entry point to the next activity in which students sort the sums into those they know and those they don’t yet know. In this activity, students may choose any sum within 10 that they like.

MLR8 Discussion Supports. During group work, invite students to take turns sharing their responses. Ask students to restate what they heard using precise mathematical language and their own words. Display the sentence frame: “I heard you say . . .” Original speakers can agree or clarify for their partner.

### Launch

• Groups of 4
• Display the addition chart from the warm-up.
• “You are going to choose your favorite sum from the addition chart. For example, my favorite sum is $$8 + 2 = 10$$ because I like sums of 10.”

### Activity

• “Pick one or two sums that are your favorite. Explain why they are your favorite using drawings, numbers, or words.”
• 4 minutes: independent work time
• “Share your favorite sums with the other students in your small group.”
• 4 minutes: small-group discussion
• Monitor for students who wrote equations with addends of 0 or 1, equations with the same addend twice, or sums of 10.

### Student Facing

Write the equation: ________________________________

Show why it is your favorite using drawings, numbers, or words.

### Activity Synthesis

• Invite previously identified students to share their favorite sums.
• “Why is this sum a favorite of yours?”

## Activity 2: Sums I’ve Got (25 minutes)

### Narrative

The purpose of this activity is for students to identify which sums within 10 they know and which they don’t know yet. Sums that students know from memory or that they have a quick mental method for should be categorized as “got it.” Consider giving each student two bags or envelopes to keep their cards separated for ease of practice. Label one bag “Got It” and the other “Not Yet.” As students know more sums from memory, they can move them to the “Got It” bag.

This activity provides an opportunity for formative assessment on students’ fluency with addition within 10. Use discretion in asking students to explain their answer, as some students will simply know the sums—or count on so quickly in their head that they may not be able to explain how they got it. These students should not be required to draw a picture to represent the sum.

Look for students who know sums such as $$3 + 4$$, $$3 + 5$$, $$6 + 3$$, and $$4 + 5$$, as these tend to be the most challenging for students and will be discussed during the lesson synthesis. After the lesson synthesis, collect the student workbook page to formatively assess sums students did not know.

Students use the addition expression cards in a future lesson.

Engagement: Develop Effort and Persistence. Support metacognition and motivation by drawing attention to the end-of-year fluency goal. “By the end of this year, we will know many sums and differences within 10. Let’s see which sums within 10 we know today, so we know which ones we can keep practicing.”
Supports accessibility for: Social-Emotional Functioning, Attention

### Required Materials

Materials to Gather

Materials to Copy

• Compare Stage 1 Addition Cards to 10

### Launch

• Groups of 2
• Give each student scissors and a set of cards.
• “First, cut out your cards and mix them up.”
• 5 minutes: independent work time
• “We saw that there are a lot of sums that you already know the value of. Let’s try some together. Give me a thumbs up when you know the value of the sum.”
• Display $$4 + 1$$.
• “How do you know this one?” (Adding 1 is quick. It’s just 1 more than the number.)
• “This is a sum that many of us know right away. Any sum that you know the value of quickly is placed in the ‘got it’ pile.”
• Display  $$5 + 3$$.
• “For this sum, I might have to count on my fingers from 5. This is a sum that I can figure out, but it takes just a bit longer. When it takes you a little longer to find the value of the sum, place that card in the ‘not yet’ pile.”

### Activity

• “Start with your cards in a pile, face down. Flip one card at a time and decide which pile it belongs in.”
• 10 minutes: independent work time
• “Record the sums that you are still working on.”
• 3 minutes: independent work time
• Monitor for sums that many students have sorted under “not yet” for the the lesson synthesis.

### Student Facing

1. Place your cards in a pile face down.
2. Flip the card and say the expression.
3. If you can say the value of the sum quickly, place it under “got it.”
4. If it takes you some time to find the value, place it under “not yet.”
got it not yet

### Activity Synthesis

• “What patterns do you see in the sums you know? Why?” (I know all the +1 sums. I know all the sums of 10.)
• “Which sums are more difficult to find?” (The sums that have two bigger numbers, like 4 + 5, are harder.)
• “By the end of the year, you are going to be able to quickly tell the sum for all the addition expressions within 10.”

## Lesson Synthesis

### Lesson Synthesis

Display three common “not yet” expressions. Consider showing expressions such as $$3 + 5$$, $$4 + 5$$, and $$6 + 3$$.

“Today we looked for sums we know, so we know which sums to continue practicing. Some students know $$3 + 5 = 8$$. What is a method you can use to help a friend who doesn’t know the value of this sum yet?” ($$3 + 5$$ is the same as $$5 + 3$$. They can count on 3 quickly. 5...6, 7, 8.)

Highlight and record 2–3 student methods for more challenging sums. These methods can be displayed in the classroom for students to refer to later in this section and unit.