Comparing the Earth to an Apple

I am taking a Historical Geology class this summer to complete my Middle School Science endorsement.  Even though I teach components of this in 4th Grade, I haven't gone nearly as in depth as I am expected to do in this course.

For instance, the first chapter alone covers the creation of Earth and the Solar System, the layers of Earth, the major features of mountain ranges and ocean ranges, the rock cycle, and the different types of rocks (and those are just the highlights).  Whew!

I have got to learn/review an enormous amount of information in a relatively short amount of time.  So I got to thinking...  The Earth kind of reminds me of an apple.  This could help me memorize the layers of the Earth.  Not to mention the fact that I just might get the chance to use this with my students before too long!

This customizable PowerPoint includes the following:
Label the layers of the Earth
Compare the (filled in) layers of the Earth to the layers of an apple
Answer key for the compare and contrast slide

You can pick up a FREE copy by clicking here.

Do you have any great tricks or resources for this information?  If so, I'd love to see it!