A treat for the eyes and ears
Every year I give my class a real treat, I show them the tuning forks. As you can see they are a truly impressive set of forks in a beautiful wooden box with a red velvet lining. Students always gasp as the lid is opened, stunned by the symmetry of their arrangement. I don't want to get them dirty but if the students are really good I might play one of them by hitting it on my shoe and resting the end on the table. It's interesting how the frequency of sound you hear directly after the fork is hit is not the same as the sound you hear when placed on the table. It seems that the fork has two modes of vibration but one is surpressed when put in contact with the table. I used to let the student touch them but one of them hit a fork on the table, so now I keep them safely hidden in the cupboard.