Friday, May 31, 2013

How Nerds Cook Hot Dogs

Yesterday we took our Pre-Calculus students outside to test their solar cookers.  The cookers had three requirements:

1) It must be parabolic and have a quadratic equation.

2) The hot dog has to be placed at the focus point to cook.

3) The hot dog in the cooker must be hotter than the test dog
   * The test dog is just a hot dog sitting in the sun (not in a cooker).

One group of students had a hot dog up to 167 degree, while the test dog was 93!!!

While the students were creating their solar cookers, they were very skeptical.  "Mrs. Oswald, are you sure this is going to work?  It's just cardboard and tin foil!!"  Almost every day, the students felt they were wasting their time.

The students were amazed!  How about that?  Math is actually useful!!!


  1. This is spectacular! If I ever teach a course with parabolas, I will be stealing this.

  2. Wow! That's fantastic! We've just been teaching quadratics.

  3. I have always wanted to do this, but I wasn't sure how it would work out. Now I HAVE to do it! Thanks for sharing!

  4. Is that it for instructions? Did you have an instruction sheet you can attach here for us teachers? I love it

    1. Awesome! I'll work on a post for the instructions.

    2. Were you ever able to post instructions for this? I would love to use this for my pre-calc class when we get to conic sections! This is an awesome idea!

    3. I'm sorry about not getting back to this. The requirements that I gave the students was that the cooker had to be parabolic, to make sure they were the students were required to hand in the equation they used along with the focus point. Once the cooker was made, they had to show me where the parabola was that they created. This was an on-going process and I could help along the way since all the cookers were created in class.

      Most of the students took a large piece of cardboard and drew a coordinate grid, then created their equation, made a table of values, plotted the points, connected the points, cut out the parabola, and then copied it on to another sheet of cardboard and cut that out too.

      I use standards based grading so they had to meet all of the following requirements in order to "pass" the outcome.

      The cooker is parabolic. Must have equation and focus point.
      The cooker is not enclosed for the greenhouse effect.
      The hotdog in the cooker must be hotter than the test dog.

  5. What materials did you start with? I'd like to assume a box or some sort of cardboard and tin foil and maybe a skewer. Did you provide cardboard or did you have the students go find it?

    Great idea. I've used solar cookers in girl scouts but didn't think of them for conics. Thanks!

    1. The students were told they could use any material they wanted, but free cardboard was easiest to work with. Some students asked about using wood, that was fine with me and it would last longer (no one used wood in the end). I do not provide the material, however, many of the students asked the custodians for cardboard and they hit the jackpot there.
      They used duct tape to hold it all together (some used a hot glue gun) and then tin foil. Finally, they used a skewer to hold the hot dog in place.