Today, my lava lamp was the lesson on convection, and we clarified that "worthless" is "totally not working for anything", and a lava lamp that wasn't doing the convection thing right wouldn't be worthless if the light was still working.
Today we discussed "cool" and "awesome". Little Fayoumis said that Mommy's co-worker who was over the other day was his best guy; I asked what about Darkside? Evidently they are all his best guys, because they are cool, and what makes them cool is that they are awesome. Clarifying further, some of the things that actually make people awesome is if they're funny, if they like games, if they have cool hair and cool clothes and like Strongbad. Then he digressed about how Strongbad had played some trick on Homestar. I firmly told him that being mean made someone mean, not cool, even if you thought they were cool, if they're being mean to someone else, it's still mean and not cool.
Then we got into thornier ethical territory: what if someone asks you if they're cool, but you think they're not cool? If you tell them they're not cool, that's mean. If you tell them they are cool, that's a lie. So what you do instead is find something that is cool about them, and talk about that! Like, if they're good at spelling, tell them that. That way, you will be telling the truth and being nice!