Jason talked about the use of handwriting analysis and what types of things to look for in handwriting when analyzing it. Then we wrote our signatures on the board and gave them slips of paper to try to "forge" our signature on. Afterwards, we collected all of their forgeries and redistributed them to different students along with our real signatures on separate slips of paper-- they were supposed to guess which one was real and which was fake. This turned out to be a lot easier than we expected because their handwriting is still pretty young looking. (If we did this again, it might be a better idea to have them guess between their own real and fake signatures.) Then they did handwriting analysis on both pairs of signatures (if we had had velum paper, we would have used that for the analysis). Next, we divided them into groups and gave each group two notes that had been ripped up. They had to separate the notes based on handwriting and then try to put the pieces together to find the message.
We worked on chromatography next. Jason explained what it was and how to do it using a video from google video. We needed glasses with alcohol or water, strips of coffee filters, something to hold the coffee filter above the glass (we paper clipped the coffee filter strips to pencils), scissors, and markers.
We had time left at the end so we did "minute mysteries" where I would say a one-sentence scenario and they would ask yes or no questions to find out what happened and why. We found these at www.math.umass.edu/~diehl/mysteries.html. The kids who didn't want to play this game read and tried to solve mysteries at kids.mysterynet.com.