[reshambabble]

Like what you're trying to do here!

It took me some time to figure out what I needed to do. Immediately, when I see "select," I think "click," so I clicked on the item instead of typing in text. Consider saying, "select images by typing in their class below."

Instead of ".classname," give an example. Also consider a pop up tutorial or a guide that shows you what to do on the very first lesson.

The list of lessons is also confusing. There needs to be something that says - this is what you've learned and what you still have to learn. Otherwise it just looks like a strange list of words from a language I don't know.

Also - consider putting the instructions on the left hand side, and putting "Learn CSS!" or something at the top instead of "Select ???." Because I read from left to right, right now I see the image first, an instruction to select something on the image (which I and others will interpret as "click on the image") and then I stop (rather than go all the way across to see the other instructions). If I see the instructions first and know exactly what to do.

Great job on this!