addictive is right!!
ya know, as a child, my parents used to get the Readers' Digest and my favorite part of that magazine, well, maybe after some of the funny stories, was called something like, Increase Your Vocabulary. It was very similar to this, one page had 20 words with 4 multiple choice answers, and you would turn the page to get the correct answer. I credit my current level of vocabulary to some extent to that magazine.
Also, in Girl Scouts, we had to learn all the native birds of Eastern North America. I am amazed how much of that knowledge has stuck with me.
Never doubt that a small group of thoughtful, committed citizens can change the world. Indeed, it is the only thing that ever has. Margaret Mead