60-Second Strategy: Mystery Number
Starting class with this fun math review activity gets students out of their seats, boosts their problem-solving skills, and promotes collaboration.
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Go to My Saved Content.“Students like puzzles, especially [in] middle school,” says St. Marys Area Middle School teacher Nick Rhoades. “So it’s a nice way to provide a little mystery and intrigue to start the day.” He’s referring to Mystery Number, a math review and warm-up activity he does with his classes every other week. “It captures their attention. It also gets them to think about skills that we’ve already discussed.”
When students enter the room and see a Mystery Number on the board, they know to start solving the clues on their own. They get into small groups of their choosing and work wherever they want, utilizing chalkboards, whiteboards, dry erase markers on their desks, or paper and pencil. Going through the hints, they work to identify the unique number that satisfies each clue.
During this time, Rhoades circulates and observes—or, on days when he’s running behind, he uses this time to take care of a quick task or run to the bathroom, since students know what to do.
Once all groups have come up with an answer, students return to their seats. They review as a class, checking the clues one at a time. Although groups sometimes come up with different answers, there is only one number that truly satisfies every clue.
Rhoades sees a lot of benefits in the activity. It helps students connect the dots between lessons. It gives him feedback about how the class is doing as a whole. “ I notice quite a rich dialogue between students when they work through these problems,” he says, “and I’m impressed with how quickly they come up with the answer. I always anticipated for them to struggle or take much longer, but most of the time it’s one of the quickest activities we do.” Why? “Kids love solving mysteries,” he laughs, “even if it’s about math.”
Mystery Number is one of seven low-prep, high-yield activities that promote math talk, number sense, and critical thinking featured by authors Ann McCoy, Joann Barnett, and Emily Combs in their book, High-Yield Routines for Grades K–8, published by NCTM.
For more math review activities that keep older students engaged, read Paige Tutt’s article for Edutopia, “14 Exceptionally Fun Math Games for Middle and High School.” Or, find more quick teaching strategies for middle school in Edutopia’s 60-Second Strategies collection.