Comparing Quantities (qualitative comparisons) is a classroom routine that make student thinking visible and supports the Standards for Mathematical Practice. It can be used at any grade level and with a wide range of content.
The basic idea is to give students two quantities, Quantity A and Quantity B, and ask students to decide if:
- Quantity A is great than Quantity B (>)
- Quantity A is less than Quantity B (<)
- Quantity A is equal to Quantity B (=)
- There is not enough information to determine (?)
Students make their conjecture and provide two reasons to support their conjecture.
Here’s a 6th grade example for ratios:
Comparing Quantities activities are most effective when they get at a big mathematical idea rather than just computation. In this 6th grade example, the big mathematical idea is understanding the difference between part:part vs. part:whole ratios.
If you are interested in using Comparing Quantities in your classroom, resources are available in this Google Drive folder. The folder contains activities for each grade level grade 5 through Algebra 2 as well as a blank template and lesson guide. If you have questions about these resources, just let me know!