Sidewalk Chalk Hyperbolas Activity

Last Tuesday was my first time to see my students since the previous Thursday thanks to the stomach bug, President’s Day, and the weekend.  My Algebra 2 students were lamenting the fact that we were stuck inside at school on a beautiful day.  It’s slowly started warming up in Oklahoma, and I couldn’t be more glad.  I don’t handle the cold well at all.  I don’t handle the heat well, either.  You could say I’m more of the spring/fall weather type.  I don’t want to have to wear a coat.  And, I don’t want to sweat.  I want it to be 68 degrees year round, or something like that.  

One student suggested that we should go outside to have class.  After all, it was a “beautiful day.”  Now, going outside wasn’t in my plans.  My plans were to spend an additional day on graphing hyperbolas and to take a quiz.

I’ve seen ideas on Pinterest where students went outside to practice graphing rational functions or inequalities using sidewalk chalk.  We haven’t reached rational functions yet, in Algebra 2.  And, it was way too cold outside when we reached inequalities in my Algebra 1 class.  So, I hadn’t had a chance to take my classes outside yet.  I did have the sidewalk chalk, sitting in my cabinet, though.

After taking attendance and going over the bellwork, I told my students to grab their notebooks and a writing utensil.  We were headed outside!  Students broken into groups of 2-3 and picked a hyperbola they had yet to graph in their notebook yet to graph on the sidewalk.

Observations.  It was windy, windy, windy!  And, at 9 a.m. in the morning, the “beautiful day” had yet to really turn beautiful yet.  It was cold.  And windy.  And, my students were soon regretting their request.

They hurried up, graphed one hyperbola on the sidewalk, and rushed back into the school building to seek warmth and respite from the wind.  They gladly finished graphing the rest of their hyperbolas in their notebook INSIDE the classroom.  

I snapped a few pictures before heading back up to my classroom.  I love the conversations that happened as a result of this group graphing process.  Not all of the work was perfect.  The graph below has an error in the vertices.  But, students were talking and asking questions of each other.  How did you figure out the asymptotes?  What is the value of a?  How do I write the ordered pairs of the vertices?

This group made an error when finding the vertices of their hyperbola. 

I also love the fact that evidence of our work was left behind for the entire school to see.  We graphed our hyperbolas write outside the front doors of the school.  So, all who entered the school that day got to see our beautiful work.

When we did our interactive notebook pages over conic sections, I made a point of making my students write out the details for each equation.  For hyperbolas, they had to identify the center, the value of a, the value of b, the equations for the asymptotes, and the ordered pairs of the vertices.  I’m glad to see that this same process carried over to their graphing on the sidewalk.

My change for next year?  Watch the weather and do this on a truly beautiful day!