I am fortunate in that I have a fairly generous budget for buying supplies for my class. I have a lot of Arduino-compatible parts available to my students. My students can pick and choose the parts that they need to use. But I need a way to keep track of parts they're using. I set up a Google Form that they use to record the parts they take from the collection. That makes it easy to see who has which parts.
When we started our exploration of Arduino I had students just writing in their notebooks or Google Docs to document what they were trying to accomplish. That was fine at first. Before too long that got a little messy when it came time for me to review what they were doing. That was partly my fault because I didn't give them a structure for recording their trials and observations.
Keeping Track of Parts and Progress With Google Sheets
To satisfy the need to keep track of parts and the need for a clear way to review what students are working on, I set up a Google Sheets template that all of my students are now following. In the Google Sheet template there is a sheet for parts used and parts needed. There is a second sheet included on which students document problems they've encountered, solutions they've tried, and solutions that worked. You can view a copy of the template right here.
Arduino Parts Suppliers
There are two suppliers that I've used for Arduino parts. Those are Elegoo and SparkFun. The Elegoo Mega 2560 (affiliate link) is a good place to start if you're looking to get started with some simple Arduino projects with your students.