This simple interactive from the University of Utah's Genetic Science Learning Center gives you the opportunity to see how various small things compare to one another. Starting with a Times 12-point font and a coffee bean, scroll along to see how much larger they are than a grain of salt, a human egg, an antibody, and, finally, a carbon atom. Also, included are some reference materials about various ways to measure the size of small things—from meters all the way down to picometers (10-12 m)—and about how such small things can best be viewed.
This resource is so simple to use and understand that it works well in a variety of settings. Teachers can use it as a starting point for beginning to talk about cells and the building blocks of all living things or to assess students' knowledge about the relative size of various microscopic cells and organisms. It also gives students a visual reference for some of the various structures that may be covered in a biology class. Additionally, it could be tied into a conversation about the role that microscopes have played in our understanding of things that cannot be viewed unaided by the human eye.
Finally, teachers also might use this as an exercise in mathematics to cover the difference in powers of ten (e.g., A paramecium is 210 x 60μm, while an antibody is 12nm. Which is bigger? By how much?)
Additional suggestions for incorporating this resource into the classroom can be found by clicking on the Teacher Resources & Lesson Plans button.