I have a set of cards with statements like these:
Some of the statements are always true, others are never or sometimes true. I give each pair of students a set of these cards and a laminated board (below). The students have to discuss and sort the statements.
Next, I ask students for feedback and I will often lead a whole class discussion highlighting some of the common misconceptions. This activity always leads to good discussion, both between the pairs and as a class. Here are pdf documents: the cards and the board. If you try it, please leave a comment telling me how it goes.