The Feeding Pump Calculator

I had a lot of challenges. First of all, I didn’t even know how to use App Inventor!  Luckily, I knew how to use Scratch which is pretty similar, but App Inventor was probably more complicated and had programming we needed to learn. The next problem was about loops. I figured out how to do the basic calculating, but there was one problem:  when I put in the coding for both types of calculations, one worked and the other didn’t because they kept on looping the answer into the other. I was stuck on this for a long time. I suggested that we separate things and make 2 calculating buttons and it worked. Another challenge was the error messages. I had to try to figure out every possible mistake that somebody could make and put different coding for lots of different error messages.