Digital callipers will give you more than accurate enough readings to build wheels. They're intuitive for most people these days. OP said he was teaching a wheelbuilding course at a co-op. I'd imagine people that are signing up to build wheels don't really care all that much about using verniers, slide rules, or even an abacus. If you're going to do it all in-depth by explaining all the calculations and how to do it on paper then yeah, teach verniers too... but digital would help you get onto the actual wheelbuilding quicker, just like using a pre-made calculator.