I bought this lesson from Patty's site (it comes with two other excellent lessons). Totally worth the $5, especially since I have used so many of the lessons she posts online for free over the last few years. If you'd like to do this lesson I would encourage you to buy her line drawing packet. You will not regret it! She lays out the process very thoroughly, makes it easy to teach, and passes along some great drawing tips.
Materials required are sharpies, drawing paper, and pastels.
Here is a slideshow I made to go along with the lesson, and some interesting things about this fascinating building are below:
St. Basil's Cathedral is in Moscow's Red Square, and was begun in 1555, during the reign and by order of Ivan the Terrible. (Ivan was actually very terrible - he was mentally unstable and prone to violent rages. Also his henchmen were brutal in their use of assassination and physical punishment). Anyway, the cathedral is designed to look (see if you can guess by looking at the slideshow pictures!) like a bonfire, flaming into the sky (this is inspired by a passage in the book of Revelations, which describes the Kingdom of God and the vivid colors therein). There is no precedent for such a building - it is an example of wild and bold creativity by the architects, and inspired many buildings that were built after in Russia and the countries around it. Note the vivid colors on each tower, and the different patterns on the exterior of the building.
(If you want, you might have a discussion about how art is able to communicate ideas without words. In this case, the architects told about their religious feelings through the shape of a building. And whenever anyone sees this building, even now 450 years after its completion, they can see what those architects believed even without stepping foot inside of it. Art can be a powerful tool.)
The domes - the bubbly things at the top of each tower - are called "onion domes" because they do in fact look quite like onions. This shape (in addition to the whole candle thing) was actually a really practical design innovation for a building in a place like Russia, that gets so much snow: the snow can't stick to the onion-y shape but rather slides right off.