Diversity is defined by Illinois Professional Teaching Standards as:
"The teacher understands how students differ in their approaches to learning and creates instructional opportunities that are adapted to diverse learners."
The 7th Grade Mexico Project on the left is evidence of a curriculum which allows diverse learners to make choices based on personal interests and skills. Option #1 is a good project for a traditional academic performer and/or a student who is interested in science. Option #2 works well for students interested in people, political movements and/or has artistic skills. Option #3 is best for a learner who is more kinesthetic (building a timeline) and has a sports interest.
My book review on Howard Gardner's "The Disciplined Mind" explores the importance of different learning styles and gives some ideas about how teachers can serve these differences.