## Path of a Tennis Ball

My Year 10 class has been investigating the Parabola. We started by brainstorming what students already knew about this shape. The photo below shows what I wrote on the board from student comments:

This proved to be a very worthwhile exercise. It not only gave me a chance to assess what students knew, but gave them a chance to verbalise their previous knowledge and experiences. Bridie felt important in contributing her experience with a parabolic “Whispering Wall” she had seen on a school camp.

Another way to approach this would be to use a sticky note website like wallwisher. See Andrew Douchy’s blog post on this as an example. The big advantage of this approach is that it can be saved online and accessed later to revise or add more notes.

Next, my Year 10’s conducted an experiment to model the parabolic path of a thrown tennis ball. Here is my report on The Path of a Tennis Ball. I produced this to show students how I wanted them to write up future reports.

In the experiment Zac threw a tennis ball (after a few practices) from the bottom right hand corner of the whiteboard. Students stood at 0.5 metre intervals and made a mark on the board where the ball had passed. The photo below shows our results of the first three throws, the first two being discarded due to human error.

Next step was to input this data into an excel spreadsheet to see if a parabolic model would “fit”. Here is a screenshot of our scatterplot:

I must admit I was surprised that we obtained such a good fit with an R squared value of 0.9969.

My students are now using a similar process to investigate whether the water falling from a fountain also follows a parabolic path.

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## About webmaths

I have been teaching Mathematics in Victorian secondary schools for 30 years. I use the www to make my maths lessons better. I hope this blog will give other teachers some ideas to try in their own classes.
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