# Learning with OpenSCAD

I’m currently teaching a class to pilot AP Computer Science Principles (will be AP for the first time in the 2016-17 school year). At the beginning of the second semester I decided to deviate from my planned curriculum and drop in a little 3D printing. I had students play with OpenSCAD. OpenSCAD is used to create 3D models with programming rather than more traditional means.
OpenSCAD is really cool for a number of reasons. If students have any experience with writing code they can dive right in. They quickly realize there are many different ways to create the same part, just as there are always multiple ways to get any program to do what you want it to. Most of these ways will involve thinking in 3-dimensional coordinates while also thinking about positive and negative space. Depending on the chosen approach students may also need to bring in a variety of mathematical knowledge and skills they’ve developed over the years.

The task I gave my students was to develop a stand/holder for their own cell phones. It took them a bit to settle into this idea. I kept getting questions like, “Do I need to plan for a case?” To which I’d reply, “I don’t know, does you phone have a case?” I really wanted them to plan for a holder for their own phone.

In the future I’ll need to put some limits on their designs. Most designs were much bigger than they needed to be, many would easily hold an iPad. Maybe I’ll put a limit on the mass of plastic they could consume. I also need to make sure their design will fit the printer. I had one that would not.

After printing their stands they all realized there were problems with their designs, things that were not obvious before they tried using the physical objects. This was a great lesson and gave us a chance to talk about rapid prototyping and iteration. Each student shared their first designs with the class so everyone could learn from each other’s mistakes. The designs were then updated to fix the problems. In the redesign I also had students add in variables for phone size. This would then allow the program to be used to make a holder for any phone by simply changing the values of the variables for phone height, width, and thickness.

Overall I really liked this assignment. Students got to use their programming knowledge in a new way with a new language. I personally delivered no instruction in OpenSCAD. Students had to rely on the principles of computer science they’d already learned, tutorials found on the net, and each other, just as they would in the real world. The task was simple enough that I knew this would not be a problem. I will be doing this again as a planned part of the curriculum next year, but I’ll add in design constraints related to size and total cost of materials.