The purpose of this activity is for students to represent addition and subtraction equations on a number line. Students consider where to begin and in which direction to draw their arrows in order to accurately represent the operation in the given equation. Throughout the activity, encourage students to explain how they know their representation matches the equation. Listen for the ways students explain how they know where to start and end their arrow, which direction they draw their arrow, and how they connect the length of the jump to the equation (MP3).

• Display the equation and blank number line for .
• Invite previously selected students to share how they represented the equation on the number line.
• Consider asking:
  • “¿Cómo ven cada número de la ecuación en la representación de ____?” // “How do you see each number in the equation in ____’s representation?”
  • “¿Cómo saben que la representación de ___ corresponde a la operación (suma o resta)?” // “How do you know ___’s representation matches the operation (addition or subtraction)?”
• As time permits, continue with the other equations.

The purpose of this activity is for students to write addition and subtraction equations to match number line representations. Students determine the operation represented by looking at the direction of the arrow. They identify the starting number, the length of the jump, and the ending number in order to write the equation. Each representation shows a relationship between the same three numbers. When students explain to each other why they think two representations are most alike, they look for and make sense of the structure of the number line and deepen their understanding of the relationship between addition and subtraction (MP3, MP7).

• Invite previously identified students to share their equations for each number line.
• Consider asking:
  • “¿Están de acuerdo o en desacuerdo? Expliquen” // “Do you agree or disagree? Explain.”
  • “¿Alguien puede explicar de otra forma por qué la ecuación de ___ corresponde a la recta numérica?” // “Can anyone explain in another way why ___’s equation matches the number line?”
• Invite previously identified students to share the number lines they feel are most alike.
• If time allows, ask, “¿En qué más se parecen las rectas numéricas? ¿En qué son diferentes?” // “In what other ways are the number lines alike? How are they different?”