The purpose of this activity is for students to match expressions to base-ten diagrams. Students then choose 2 of the expressions to find the value of, using any method that makes sense to them. Some of the expressions do not require composing or decomposing a ten. A matching task gives students opportunities to analyze expressions and diagrams closely to look for and make sense of structure (MP7).

• Invite previously selected students to share how they chose expressions to solve.
• Consider asking:
  • “¿Qué expresiones escogieron para resolver? ¿Por qué?” // “Which expressions did you choose to solve? Why?” (I chose because it was easy for me. I knew that I could just add the ones and then add the tens.)
  • “¿Cómo pueden saber si necesitan componer o descomponer una decena?” // “How could you tell if you would need to compose or decompose a ten?” (I could see that , so I knew I wouldn’t need to compose a ten.)

The purpose of this activity is for students to add and subtract within 100 using the methods that make sense to them. Throughout the activity, students share their methods for adding and subtracting and compare their methods with others (MP3).

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

• “¿En qué son diferentes las maneras como están representados los métodos en cada presentación?” // “How are the methods represented differently in each display?”
• “¿Cómo encontró cada grupo el mismo valor si usaron métodos tan diferentes?” // “How did each group find the same value when they used such different methods?”

• 5–7 minutes: Gallery Walk
• “¿En qué se parecen la manera como _____ encontró el valor y la manera como _____ lo encontró?” // “What was the same about how _____ found the value and _____ found the value?” (In the first problem, _____ and _____ both added the ones and added the tens and then combined the two sums. , , )
• “¿En qué son diferentes la manera como _____ representó cómo pensó y la manera como _____ lo representó?” // “What is different about how _____ represented their thinking and ______ represented theirs?” ( _____ used a diagram and crossed out the ones and then decomposed a ten. Then _____ crossed out the rest of the ones and the tens. _____ wrote equations to show each step.)