Wonder of a Quick Assessment Tool: Glass, Bug, Mud

As I was sitting relaxing on christmas break a thought came across my mind, ‘I need a quick assessment tool in math to help with quick differentiation”. I pondered the idea for a while and remembered I had read an article on just that topic in one of my education courses a while ago. Once I had dredged up the name of the article from my memory I started looking into the ins and outs of the assessment tool (incase you’re wondering it’s called, Glass, bug, mud).

The glass, bug and mud assessment tool works with a simple analogy of imagining your understanding is the driver of a car. If you understand a concept you are glass, all is clear and you can see the road. If you kind-of get it you are bugs and see some of the road ahead. Finally, if you are mud your view is almost completely blocked and you don’t understand the concept or question. My goal was to have students quickly self-assess and to help me with my groupings during our math stations in math.

To get the concept of glass, bug, mud going in my classroom I created a small graphic inspired from Freshly Sharpened Pencils and it stuck on the top of my whiteboard.


C.C. “Glass, bug mud” Mary Bertram

Once the graphic was up the fun began. I played a game with my students to see what their evaluation of understanding was of everyday activities with three corners of the classroom representing glass, bug and mud. I asked questions like “What is your understanding of the rules of baseball?” or “Do you understand the rules for kickball?” and the students would move to the appropriate corner. They loved the game and we played it for a good 15 minutes before recess. Later that day I asked all the students to stand up and whether they were glass, bug or mud in their understanding of the topic just covered. They quickly and easily moved to the corner their understanding was at.*It must be noted that I have worked hard to create a sense of community in my classroom this year where weakness is accepted and celebrated as a learning opportunity. I know some students get self-conscious with this type of self-assessment but that is a post for another time.* The rest of the week after we completed work I would ask them where their understanding was at and they would let me know without hesitation. (They actually asked multiple times if we could check our understanding and play glass, bug and mud! You have to love grade 4 enthusiasm)

I hadn’t thought about it much this week as we had a windchill day on Monday and only 5 students made it to school on Wednesday but today is when the MAGIC happened….

I was fumbling my way through a lesson that was nosediving quickly. After explaining something twice to the students one of them said “Miss Bertram. I have to be honest I am at mud right now. I have no idea what you are trying to tell us”. Then slowly a few students responded “Yeah, I am at mud too…”. I smiled as realized I too was in the mud and was glad for our new glass, bug and mud tool.


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