The purpose of this activity is for students to demonstrate methods they have for addition and subtraction within 10. In this activity, students draw 2 cards and consider how they could add or subtract the numbers to create a value that matches one of the target numbers (0–10). Listen for the ways students think about how to find the value of sums and differences, including any sums and differences they know from memory, and how they share their thinking with their partner. If students disagree about the value of a sum or difference, encourage them to discuss their reasoning and reach an agreement (MP3).

Students may write subtraction expressions that do not match their computation. For example, students write 2−4 instead of 4−2. Ask students to use counters or cubes to represent the subtraction. Highlight that they started with 4 and took away 2 and ask them to connect this action to the expression. To stay mathematically consistent with what students will learn in later grades about operations with rational numbers, avoid language that suggests students can only subtract a smaller number from a larger number.

• “¿Escribieron algunas expresiones que correspondieran al mismo valor? ¿Qué número era? ¿Cuáles eran las expresiones?” // “Did you write any expressions that matched the same value? What number was it? What were the expressions?"
• “¿Hubo algunos valores que ustedes y su pareja no encontraron? ¿Qué expresiones pueden corresponder a estos números?” // "Were there any values that you and your partner did not find? What are some expressions that could match these numbers?"
• If needed ask,
  • “¿Qué expresiones obtuvieron para 5?” // “What expressions did you get for 5?” (I found and  .)
  • “¿Qué expresiones obtuvieron para 0?” // “What expressions did you get for 0?” (I found and .)
  • “¿Qué expresiones obtuvieron para 10?” // “What expressions did you get for 10?” (I found and .)

The purpose of the activity is for students to practice finding the value of sums and differences within 10. Students also identify addition expressions that have a value of 10. Students will work more with sums of 10 in the next lesson. This activity provides an opportunity to observe how students find sums and differences within 10, including those they know from memory.

• Ask students to share answers to problem 3.
• Record responses.