Video is such an elegant means to share knowledge. It can teach without superfluous explanation (just as we should!). Michael Olaf offers a video library showcasing work for children from 0 to 3 years old.
I also would recommend ordering their catalogs. Not only are their products well-curated, each page is divided such that half showcases their wares – while the other half reads like an introduction to child development. An inexpensive resource book with pictures – now that is hard to beat! Happy exploring!