DIY Borax crystal Snowflakes - this site suggests you could spray with a spray enamel to keep it from dehydrating and turning back to powder. needs to be kept out of the reach of small children (who might put in mouth).
This tornado in a jar would be a great visual for a science lesson. It is easy to make and interactive. The students can shake the jar in a circle to get the tornado formation and see its shape and how it moves. Adding "Elijah" to the jar?