VIRUSES lesson 2: Size and prevalence


I have divided this lesson into two videos.  

The first runs 38 minutes and the second is only 18 minutes.

(NOTE:  For any younger students who are not likely to go much further than this lesson, don’t quit before you check out lesson 7(a), and the activity suggestion about making virus cookies.)

In lesson 2(a) we learn how big viruses are.  To do that, we need to learn about three units of measure:  the millimeter, the micron (or micrometer), and the nanometer.  We will make a scale drawing so that it will be easy to see the range of viral sizes

You will need a pencil, eraser, and a small piece of scrap paper.

Download and print the template page before you begin watching the video.

Virus lesson 2a template page

The info page for this drawing is here:

Virus lesson 2 info page

If you need to see the final drawing, here is a copy of the one I drew on camera:

Virus drawing 2(a) sample


In lesson 2(b) we will find out that we live in a cloud of viruses, with millions of viruses living in us, on us, and around us.  We learn that virus prevalence is measured using exponents because the numbers are so large.  We write some very large numbers!

Download and print this template page before starting the video:

Virus lesson 2b template page




Activity 2.1:  An interactive online demo about scale

You can zoom in or out to see the relative sizes of small things, from a coffee bean down to a carbon atom.








Ready to take the quiz?   (Not required)  15 questions, and you can take it more than once.

(If the online quiz isn’t working, try turning off your ad blocker.  I’ve heard that can fix the problem.)

If you would like a printed copy of the quiz, you can use this PDF version.  The PDF gives you both the quiz and the answer key.

Virology quiz lesson 2



Back to: Intro to VIROLOGY