The purpose of this activity is for students to interpret and solve Compare problems involving length where the language suggests an incorrect operation. For example, the first problem uses the word “shorter” which usually suggests subtraction. However, in this problem students are looking for an unknown that is the greater length and must add the two known values.

The Three Reads routine is used to help students practice making sense of the problem before solving. Students begin the activity by looking at the first problem displayed, rather than in their books. At the end of the Launch, students open their books and work to find the diagram that matches the story problem. This helps students visualize the quantities in the problem before they work to find a solution (MP1).

After reading the other story problems, students consider which pet is longer or shorter and choose tape diagrams to match the lengths in the problem (MP2). Students solve each story problem independently and compare their solutions.

This activity uses MLR6 Three Reads. Advances: Reading, Listening, Representing

• Invite students to share the correct diagram for the second problem.
• Display the diagram.
• Consider asking:
  • “¿De qué manera el diagrama corresponde al problema-historia?” // “How does the diagram match the story problem?” (You can see that Mai’s rectangle is longer and there is a question mark for Diego’s pet.)
  • “¿Cómo supieron cuál mascota era más corta?” // “How did you know which pet was shorter?” (It said that Mai’s snake was 17 cm longer, so Diego’s is shorter.)

The purpose of this activity is for students to make sense of and solve Compare story problems involving length. Students use measurements provided for reptiles and create their own Compare problems to solve with a partner. Students must solve a Compare, Difference Unknown problem when creating their mystery problem. When they solve their partner's mystery problem, they must solve a Compare, Bigger Unknown or Compare, Smaller Unknown problem. Encourage students to use diagrams or other drawings to show how they know which reptiles their partner picked. Some students may choose to use equations to represent the lengths.

• Invite previously identified students to share how they determined their partner’s reptiles.
• Consider asking:
  • “¿Cuál reptil era más corto? ¿Cómo se muestra esto en su diagrama?” // “Which reptile was shorter? How does your diagram show this?”
  • “¿Sumaron o restaron para encontrar el otro reptil? ¿Cómo les ayudó su diagrama?” // “Did you add or subtract to find the other reptile? How did your diagram help you?”