The purpose of this activity is for students to create and describe rectangles of a certain area. Students work in groups of 2. One partner creates a rectangle and describes it, and the other partner creates a matching rectangle, based on the description. Then students compare how their rectangles are the same and how they are different. Students should describe their rectangles to their partners without revealing the total numbers of squares they used, so that the focus is on understanding the rectangular structure. In the Activity Synthesis, students share language that helped them understand the rectangles their partners built. When students revise their language to be more precise in the descriptions of their rectangles, they attend to precision (MP6).

• “¿Qué lenguaje usó su compañero que les ayudó más cuando estaban dibujando el mismo rectángulo que dibujó su compañero?” //  “What language did your partner use that was most helpful to you when you were drawing the same rectangle they drew?” (Helpful language included “the number of squares in each row (or column)” and “the number of rows (or columns).”)

The purpose of this activity is for students to find the areas of rectangles by counting squares. Larger rectangles provide more opportunities for students to practice counting strategies, using the structure of the rectangles to group the individual squares (MP7). Rectangles in this activity lend themselves to show groups of twos, fives, or tens in rows or columns. Students may also see other ways to create equal groups within rectangles. For example, the second rectangle, with an area of 30 square units, can be seen as 3 groups of 10. If students finish quickly, encourage them to confirm their areas by counting another way. Emphasize that each area is in square units.

• “Dime cómo contaste los cuadrados” // “Tell me how you counted the squares.”
• “Cuando cuentas los cuadrados, ¿cómo puedes saber qué cuadrados ya contaste?” // “How could you keep track of your count as you count the squares?”

• Invite 3 or 4 previously selected students to share how they found the area of one of the rectangles. Try to highlight a variety of strategies.
• Consider asking, “¿Su estrategia cambió de un rectángulo a otro?” // “Did your strategy change from rectangle to rectangle?”