Let's look into vertebrates!  I never thought that doing a lesson on the spinal column could be both cute and entertaining, but as I was working on a lesson for third graders on vertebrates and invertebrates, I ran across at least four extremely easy, entertaining, and very child-friendly ways o make spinal columns a concrete, non-gross, and understandable thing for elementary school kids.  They don't take much in the way of supplies, it's an activity that comes off as fun to the students, and uses sensory and other learning skills, so teacher gets a break from talking,a nd studets get a break from staring into space and nodding!
Here's some of the ones I really like:  

This one might be the easiest, from: http://bishopsfamilysite.blogspot.com/2013/10/vertebrate-science-craft.html




This one I like because it visually shows how muscles are supported on the spine: http://shenanigansinsecond.blogspot.com/2012/04/sunday-rewindanimals-and-poetry.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed:+2ndGradeShenanigans+%282nd+Grade+Shenanigans%29


This is the one everyone would be tempted to eat: http://inspiremeasap.blogspot.com/

 
This one is the most in-depth, and possible cutest, best for students ready to make connections to other ideas in biology.
http://www.parents.com/blogs/homeschool-den/2013/01/15/science/meet-vertebrae-man-our-hands-on-explorations-of-the-backbone-and-nervous-system/