The purpose of this activity is for students to identify the attributes that make a quadrilateral a rectangle, a rhombus, or a square. Students study examples and non-examples, looking for features that each set has in common and draw conclusions accordingly (MP7). The goal is not to craft the most precise definition for each, but to develop an understanding of the defining geometric attributes.

• Invite 1–2 groups who analyzed rectangles to share their responses. Record their responses.
• Ask the class:
  • “¿Están de acuerdo en que las figuras marcadas son rectángulos (o rombos o cuadrados)?” // “Do you agree with the shapes that are marked as rectangles (or rhombuses or squares)?”
  • “¿Están de acuerdo en las descripciones?” // “Do you agree with the descriptions?”
  • “¿Hay alguna parte de las descripciones que dirían de otra manera?” // “Is there any part of the descriptions you’d say differently?”
  • “¿Le agregarían algo a la descripción?” // “Is there anything you'd add to the description?”
• When students have finished describing rectangles, highlight that: “Una figura es un rectángulo si es un cuadrilátero que tiene 4 ángulos rectos” // “A shape is a rectangle if it is a quadrilateral with 4 right angles.”
• Repeat the discussion with rhombuses and squares. Highlight that:
  • “Una figura es un rombo si es un cuadrilátero que tiene lados iguales” // “A shape is a rhombus if it is a quadrilateral with equal sides."
  • “Una figura es un cuadrado si es un cuadrilátero que tiene lados iguales y 4 ángulos rectos” // "A shape is a square if it is a quadrilateral with equal sides and 4 right angles."