I don't know where I found this (whose blog was it!) or when, but I've been printing a lot of the Teacher's Guides from this site. It is a wonderful resource for Earth Science.
I thought I'd share because while we are doing a few of the units now (minerals, gems, etc.) I'm definitely printing the rest out for next year's mini-science units I'm planning.
Click on the unit you're interested in, then click the bottom right "Teacher Corner" for the great guides.
I even used bits and pieces of this for Cub Scouts. A lotta bang for the buck here!
Edited: Thanks for letting me know about the extra http:// It has been fixed!