I asked Mr. Randall about sig figs for this lab, especially on instruments like the vernier caliper and micrometer. This was his answer: "For lengths smaller than 1 cm, you should get at least 2 sigs: 0.??. (To the 100th place, 0.01.) Between 1 cm and 9.99 cm, you should get 3: ?.?? The Vernier scale digit takes the place of your “uncertain” digit. I’ve read articles that suggest if the Vernier scale line manages to fall between marks, readers are allowed to guess the 1000th digit, but I’ve never noticed that situation on a scale so small. I’m not expecting any values below the 0.01 place. But the micrometer caliper scale can give you guessing capability at the 0.001 mm level, so 1.23 cm on a Vernier scale might read as 12.345 mm on the micrometer caliper." I hope this helps anyone struggling as I was!