J. D. Harding wrote a book way back in 1854 that still has solid-gold advice for art and architecture students today.
He suggested making models of architecture to use as drawing subjects.
They teach you perspective and light and shade in a way that nothing else can. The geometric forms are a good supplement to the organic shapes of figure and cast drawing.
The book shows roof plans for various grand estates. If you’ve got a wood shop, you can cut all the various architectural pieces out of larger pieces of wood. The model pieces also make great blocks for kids to build with. Nowadays you could also use build them out of cardboard or foam core board, or cut them out of a dense foam.
His book, “Drawing Models and Their Uses” is available as a free download from Google Books.
Drawing Models and Their Uses from Google Books (click the "Download PDF" button at the right side of the page)