Instead of starting Shadows with the learning goal, ”Understand that for similar triangles, the quotient of two side lengths in one triangle is equal to the quotient of the corresponding side lengths in the other triangle,” which students aren’t likely to connect with a concrete experience, consider starting instead with a comprehensible, intriguing question:
What can shadows tell you about the time of day? What can shadows tell you about the object casting the shadow?
These kinds of questions are likely to help students organize their work, make the leap to triangles in the plane, and share more of their thinking, which will help you when you share the learning goal later.
Have fun with this one!
Dan & the Desmos Classroom Team
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Great advice from other teachers.
Eagle, CO
Capitalize on those pivotal moments [in] slide 2 and slide 4! Make sure kids know they have options when solving and that mathematicians look for the most efficient way to get the job done!
West Chester, PA
Think through how you want students to solve for the unknown side lengths on slides 4 and 5. We debated setting up equations, just using a fraction or decimal representation to multiply– ultimately go with what your students make sense of, but they will want to guess and check if they are stuck, so have some advancing questions ready just in case.
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