In French, there are two different ways to say "I know": je connais or je sais. The verbs are connaître and savoir. The one you use depends on what you "know". Connaître is more of a knowing/being acquainted with people/ideas/places whereas savoir is for facts and abilities.
My students have always had such a hard time knowing the difference between the two...heck even I have a hard time distinguishing between the two sometimes.
So I made an activity. It was quite simple actually. Almost too simple. We made two columns. One said "je sais" at the top and the other said "je connais". I then made a word bank of different things one would know, and their task was to put them in the appropriate column. We then discussed it so that they could check their answers. Then we just looked at them. Earlier in the unit, the kids looked at me funny when I said it's just something you eventually "get". But in looking at the columns, I believe they finally "got" it. There's just a feel for when you use savoir and when you use connaître. And based on the work they have done since, I can tell they really get it now.
Who'da thunk that it would be something as simple as COLUMNS?