Spreadsheet Shortcuts

10 min

Narrative

The purpose of this activity is to prepare students to work with a table of equivalent ratios that appears in a later activity in this lesson.

Launch

Give students a few minutes to complete the table. Ensure that they found the correct values before they work on the second question.

Student Task

Here is a table of equivalent ratios:

aa bb
3 15
10 50
6 30
1  
  80
  1. Complete the table with the missing values.
  2. Explain what it means to say that the pairs of numbers are equivalent ratios.

Sample Response

aa bb
3 15
10 50
6 30
1 5
16 80
  1. See table.
  2. Possible response: Each value in column bb results from multiplying the value in column aa by 5.
Activity Synthesis (Teacher Notes)

Invite students to share how they reasoned about the values needed to complete the table. Keep asking "Did anyone think about it a different way?" until a few ways of reasoning come to light. Some methods might include:

  • Multiplying any number in the first column by 5 to find the number in the second column
  • Dividing any number in the second column by 5 (or multiplying by 15\frac15 to find the number in the first column)
  • Using a scale factor to move from row to row, for example, starting with 6 and 30, you can multiply each value by 16\frac16 to find 1 and 5 in the next row.