How do you estimate the size of something microscopic?

Question

I have a science test tomorrow, I kinda have to know.

teacher wasn't there today, I lost my sheet and it's not in the text.

Answer 1

It's hard to explain if you haven't done it before, so use some imagination.

When you're looking at your object under the microscope, estimate how much of the "field of vision" it occupies as a fraction. Write it down. Now, stick one of those clear rulers underneath the microscope; do NOT adjust the settings of the microscope. You can now measure the actual length of the field of vision.
Now some math:
(fraction of FOV of the object) x (actual length of FOV) = approximate size.

At the end of it all, you'll probably want to convert to smaller units, like micrometers/microns.

Answer 2

Most microscope software have a tool for putting in a ruler at the bottom of a microscopic objects photograph. Based on the ruler you can tell how big the object is.

Answer 3

Aw, honey, you should have asked us, sooner!

Or, better still, you should have asked the teacher
or read the text book!