Here's a cool website for teaching about art theory. The target audience is kids - and I doubt that many of you grown-ups will learn too much from it - except to confirm that you're pretty smart about art already - even if you don't know all the technical terms. ;-)
However - it would be a cool site to sit down at with your kids or grandkids, nieces and nephews, etc. The learning part is fun - there is a short presentation on the topic in question, and then a practical application of it - which really needs your input for feedback - more fun with the two of you.
The exploration phase - where you get to play and put the theory into practice - that's a lot of fun. It's all intuitive and encourage playing.
The Artist's Tool Kit
And when it comes down to it - we beady people know that Art is important - it surrounds us every day and makes our lives better!