I thought these two projects from Martha Stewart’s website are good ways to recycle those baby food jars. To prevent a toddler from unscrewing the lid, I would suggest hot-glue it to the jar. Also, please supervise closely in case of breakage.

FIREWORKS IN A JAR
http://www.marthastewart.com/page.jh...&layout=martha

OCEAN IN A BOTTLE
http://www.marthastewart.com/page.jh...&layout=martha