There is a lot of educational information on the web that you can use in your lessons. A LOT. Videos, images, articles, documents, diagrams, games, exercises, oh my.
However, quality can vary significantly. There are many lumps of coals out there. So every time you come across a high-quality gem, give yourself a high-five! Then take note of it somewhere.
As your collection of gems grows, you may have colleagues who will find your curated resources very helpful. You may even find their curated resources helpful as well.
Via Gumersindo Fernández, Alberto del Mazo