The University of Utah's Genetic Science Learning Center offers two sites for learning the basics of DNA:
LearnGenetics: Here, you’ll be presented with an animated tour of DNA, videos that explain how genetic traits are passed from one generation to the next, and a look inside of a cell. You can see how cells compare in size to molecules, atoms, and other objects, and build a DNA molecule.
TeachGenetics: The companion website to the one above, here, you’ll find ready-to-use “print-and-go” activities with instructions, worksheets, visuals, and answer keys. For example, you can download Have Your DNA and Eat It Too which includes instructions for making edible DNA with Twizzlers and mini marshmallows.
More Readings, Videos and Activities:
Glencoe textbook chapters on: Mendel and Meiosis; DNA and Genes; Patterns of Heredity; Genetic Technology.
Punnett Squares Virtual Lab
Make a Monster Traits Activity and Instructions
Howard Hughes Medical Institute: Learn about DNA, stem cells, and genomics and chemical genetics, among other topics. Most topics feature videos, animations, interactives, and articles. In the “Classroom” section of the site, you will find activities and teachers guides.
DNA From the Beginning: Readings, animations and videos covering topics in Genetics.
BrainPop on Heredity