A Sidewalk Investigation of Radians

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SWBAT discover and explain the concept of a radian with a shoe string and sidewalk chalk.

Big Idea

If the shoe [string] fits...?!

Explanation and Transition Outdoors

5 minutes

In this early-summer lesson, the students have an opportunity to get outside, enjoy some sunshine and investigate radians.  With trig being a relatively new Algebra 2 concept (Common Core), it is important to provide the students with a solid entry point of understanding what they will be working with.  This roll-out lesson has students work hands-on with sidewalk chalk and a shoestring to build an understanding of radian measurement and how this connects to the unit circle.  

The materials needed are listed in the Side Walk Investigation sheet I circulate to the students.  As stated at the top, I prefer my students work in groups of three.  I make the groups but you can decide what works best for your class. The reason for three is that this allows for one person on the string, one person on the chalk, and one person to records and offers support (MP5).  This group effort provides a opportunity for students to engage in constructing arguments and critiquing the reasoning of others (MP3).


Make sure each student receives a copy of the Side Walk Investigation - Data Sheet to record their results.  Despite initial moans and groans, I let student know that they will use these notes later and they need a record of their own data even though they are working in teams of three (MP6).

This might be a silly reminder, but make sure that you put a sign on your door letting anyone who visits (or any students who arrive to class late) that you are outside in the parking lot!


Investigation Time!

30 minutes

Homework Time

10 minutes

To conclude class I assist any remaining groups in finishing up.  Typically speaking, there is a group or two that failed to follow directions.  The rest of the class picks up the Homework while this is going on.  This worksheet is due tomorrow at the start of class.  Although it is an individual assignment, I do not get too worked up in this case if the students collaborate with each other as they complete it.  

As long as the weather is cooperative, we remain outdoors and soak up the sunshine as we work.  It is a nice surprise for the kids to have math class outside for a change!