I love doing science show and tell with students. They make great demonstrations and in some cases great activities for the kids to try. I like to do them at the beginning of class. It peaks there interest. I have also noticed an increase in their abilities to write about science. The more I do it the longer they write. Here is a fun one to try.
Want more Science Show and Tell. Here is a nice collection in a digital download format. Available on my Teacherspayteachers.com Store.