Mass - Use the triple-balance beam to measure mass
Bugscope -
Brainpop - classification - Good for introduction
Critters Quest in Pennsylvania - PA species search
Organize It: Test yourself on Biology Categories
Genetics
Learn Genetics - Genetic Science Learning Center from The University of Utah
Human eye color - Eye color calculator.
Genetics Project - From the Montgomery Schools.
Understanding Genetics: Human Health and the Genome.
Square of Life - Collaborative project from CIESE
Siemens Science - Learning by doing.
Cells -
Insect images from Iowa State University.
Animal images from Colorado State University.
Pics4Learning - search topics