I always love it when Dan decides to show the kids how something works. Recently, he had to use his caliper to measure the tubing on my bicycle seat. So, he took the opportunity to show the kids the measuring device and how to use it. Have you ever seen the Vernier scale on a caliper? It’s used to measure increments smaller than 1mm.
I should point out that the Vernier scale isn’t just used to measure out increments smaller than a mm, but smaller than the smallest increment on your measuring tool which in this case was a caliper with mms on it.