Gluesticks has a great tutorial for how to make rock candy. All you need is sugar, water, food coloring, and some bamboo skewers. These are great to make for parties or just a fun project.
Good for ages 6 and up.
Get the instructions here:
http://brandyscrafts.blogspot.com/2011/09/homemade-rock-candy.html
Fancy shanty shares a recipe too.
Get the instructions here:
http://fancyshanty.com/2013/04/homemade-rock-candy-recipe/
Growing a jeweled rose watches it grow and observes its progress each day. Note: it looks bigger in the jar than it actually is.
Get the instructions here:
http://www.growingajeweledrose.com/2015/02/rock-candy-experiment.html