Please include this image for this lesson? Answered
Normally PCBs with accessible pin banks like the 40 pin GPIO on the R-Pi have an indicator identifying "pin 1" so one knows where to start counting. You don't give that info in the lesson and (as far as I can see on my Pi) it's not indicated on the board. This is important. When I internet searched I found more than pin numbering scheme--likely for different models--but it took time for me to locate the image below that clearly shows the location of pin 1.