For the last couple years, I have been using a puzzle to introduce the periodic table unit to my students. After a quiz, I give them a ‘puzzle’ to work on in their lab groups. It consists of squares with four different colored values. They have to look at the trends in each and build a rectangle where everything fits. As they work, they realize that they are missing a piece. So I hand them a blank piece that they then predict the values of that missing piece. Then I give them two more pieces that go around the outside somewhere. Once they get these two pieces in place, I show them a predict table and they realize they just constructed it just like Mendeleev did! But without knowing anything about the elements but a few properties.
This year I added invisible ink and a uv flashlight to make the reveal even more fun. 🙂 Here are the pieces before I cut them out.