In this activity students subtract 2 values and recall that the distance between the values on the number line is given by the lesser value subtracted from the greater value. Students critique a statement or response that is intentionally unclear, incorrect, or incomplete and improve it by clarifying meaning, correcting errors, and adding details (MP3).

The purpose of the discussion is to find an algorithm for finding the distance between two numbers on the number line.

Use Critique, Correct, Clarify to give students an opportunity to improve a sample written response to the last question by correcting errors, clarifying meaning, and adding details.

• Display this first draft:
  Subtract them. For example, if the numbers were 8 and 2, I would do . If the numbers were 3 and 12, I would do .
  Ask, “What parts of this response are unclear, incorrect, or incomplete?” As students respond, annotate the display with 2–3 ideas to indicate the parts of the writing that could use improvement.
• Give students 2–4 minutes to work with a partner to revise the first draft.
• Select 1–2 students or groups to slowly read aloud their draft. Record for all to see as each draft is shared. Then invite the whole class to contribute additional language and edits to make the final draft even more clear and more convincing.

In this activity, students find 2 numbers that are a given distance from a number. In the associated Algebra 1 lesson students find the positive difference between 2 values by figuring out how far away a guess is from an actual value. Students look for and make use of structure when applying their knowledge of distance to situations in context.

The purpose of the discussion is for students to think more deeply about distances on the number line. Select students to share their responses. Here are some questions for discussion:

• “How far apart are 85 and 31 on the number line? What is another number that is the same distance away from 31?” (They are 54 apart. -23 is also 54 away from 31.)
• “In most places in the United States, houses on the same side of the street are either all even numbers or odd numbers. Does this affect the answer to the question about the planned neighborhood?” (No. It would affect how I might draw the picture (for example, there may only be 9 houses between 84 and 102 Stepford Street), but the same numbering would happen on the other side of the house at 84 Stepford.)