Probes

A probe is a problem given to students periodically to assess where they are in developing the thinking strategies. The following is an example of a “Count Back To Subtract” Probe given to students on day 5 of using the Count Back To Subtract 5 minute lessons.

Example

Problem: Derrik has 12 markers. Shannon has 1 marker. How many more markers does Derrik have than Shannon?

Connections: Highlight an interesting strategy and have all students try it with:

Suppose Derrik has 7 markers in his box. If Shannon borrows 2 of them, how many markers are still in Derrik’s box?

As students explain their strategies, ask how many other students used the same strategy. Record the number to show class progress over time.

Strategies Used	Number of Students
Count all
Count up
Count back
Use known fact
Use addition
Just know