The purpose of this activity is for students to practice adding within 1,000, with an emphasis on adding by place. Throughout the activity, students have opportunities to explain their methods and representations to peers. In the Activity Synthesis, students have opportunities to question and critique the work of their peers as they compare different methods for adding three-digit numbers and different representations that show composing units when adding by place (MP3).

This activity uses MLR8 Discussion Supports. Advances: conversing.

• “¿Cómo muestra tu representación que compusiste una unidad en base diez nueva?” // “How does your representation show that you composed a new unit?”
• “¿Qué podrías agregarle a tu representación para mostrar las decenas o centenas que compones?” // “What could you add to your representation to help you keep track of any tens or hundreds you compose?”

• Invite 2 or 3 previously identified students to share their representations and how they found the values of the sums.
• “¿En qué se parecen estos métodos? ¿En qué son diferentes?” // “How are these methods the same? How are they different?”

• “¿En qué se parecen el trabajo de Noah y el de Kiran? ¿En qué son diferentes?” // “How is Noah and Kiran’s work the same? How is it different?” (Both show adding by place. Noah used a base-ten diagram and Kiran used equations. They found different values. Noah forgot to add the ten he made from the ones. He had enough tens to make a hundred.)
• “¿Cuál estudiante encontró el valor correcto de ​​? ¿Cómo lo saben?” // “Which student found the correct value for ? How do you know?”
• Invite previously identified students to share.
• Consider asking:
  • “¿Qué paso del trabajo de Kiran le hizo falta a Noah?” // “Which step in Kiran’s work did Noah miss?”