The purpose of this activity is for students to revisit Stage 1 of the How Close? center, which was first introduced in grade 1. Students pick 5 digit cards and then choose 3 to make an addition equation with three addends and a value as close as possible to the target number of 20. The student with a sum closest to 20 gets a point for that round. Students may use a variety of strategies such as making a 10 to add two numbers or using the relationship between addition and subtraction to strategically choose three numbers (MP7).

• “¿Qué métodos usaron para encontrar una suma cercana a 20?” // “What methods did you use to find a sum close to 20?”
• Invite previously selected students to share their strategies.

The purpose of this activity is for students to add and subtract within 20 using any method that makes sense to them. In the previous activity, students shared methods they used to add within 20. This activity gives students an opportunity to try some of the methods they discussed. In this activity, students also subtract within 20 and discuss their methods in the Activity Synthesis.

If students are counting all of the cubes by 1 or working with loose cubes, consider asking:

• “¿Cómo encontraste el valor de  _____?” // "How did you find the value of _____?"
• “¿Cómo usarías las torres de 10 como ayuda para encontrar las sumas o las diferencias?” // "How could you use towers of 10 to help you find the sums or differences?"

• Display 17 – 9.
• Select previously identified students to share their strategies.