The purpose of this activity is for students to solve a Take From, Result Unknown problem, which requires decomposing a ten, in a way that makes sense to them. The problem is presented with an image that encourages students to think about 16 as a ten and 6 ones. They create a poster to share how they solved the problem, and participate in a Gallery Walk to see how their classmates solved. As students are working, the teacher monitors for methods to analyze during the Activity Synthesis. As they do so, students connect addition and subtraction and see how either can be used to solve the problem (MP7).

This activity uses MLR7 Compare and Connect. Advances: representing, conversing

• Give each group tools for creating a visual display.
• “Hagan un póster que muestre cómo pensaron sobre el problema. Asegúrense de hacerlo de una forma que los demás entiendan” // “Create a poster that shows your thinking about the problem. Make sure to show your thinking in a way others will understand.”
• 5 minutes: partner work time
• “Mientras caminan y observan los pósteres, piensen en qué se parecen los pósteres y en qué son diferentes” // “As you walk around and look at the posters, think about how the work is the same and different.”
• 5 minutes: Gallery Walk
• “¿En qué se parecen y en qué son diferentes las representaciones?” // “What is the same and what is different about the representations?” (They all showed 16 and 7. They used math tools to represent the problem. Some people used addition facts they knew, some counted up, and some took away.)

The purpose of this activity is for students to subtract a one-digit number from a teen number. Students choose a teen number card, then choose a number card to subtract from the teen number. They write an equation to represent each round. The equations students write may involve subtraction, or addition with an unknown addend. During the Synthesis, students share their methods. When explaining, students have opportunities to revise their language to make their explanations more precise and clear (MP6).

Students play this game again in the next lesson with a double 10-frame, so keep the materials organized for future use.

• Invite previously identified students to share.
• “¿Cuál de los métodos que vieron hoy les gustaría probar?” // “What method did you see today that you would like to try?”