There are over 100 simulations on their website, all are FREE! Many of the older ones, such as Gas Properties, require Java and can only run on a computer. The newer ones, such as Balancing Chemical Equations, have been converted to HTML5.
The simulations are not limited to Chemistry topics. There are also simulations for Biology, Physics, Earth Science, and Math.
Mobile app versions are available for iOS and Android devices for a nominal fee.
DNA Interactive (http://www.dnai.org/), in conjunction with DNA Learning Center, is an amazing resource with interactive activities for students: Timeline of discoveries in genes and molecular biology, how DNA and its structure provide the basis for genes and gene expression. The animations on DNA replication, transcription, and translation are SUPERB. I started using these when they came out on DVD. I’m so glad they have these animations available on YouTube now as well. Here’s the one on DNA Transcription.
Teachers can register for a free account with access to resources: teacher’s guide, student worksheets, answer sheets.
One warning: the site does not work on the iPads since it requires Flash to work.
In my Biology curriculum, natural selection and evolution are heavily stressed. To help students understand these concepts, I use the HHMI BioInteractive on the Making of the Fittest. The lesson plan on Rock Pocket Mice is very good. My 9th grade Biology students enjoy learning about these furry little mice and how a change in the environment has changed their allele frequency over time. There’s a pre-test as well as a post-test to gauge student’s understanding.
The Botany of Desire is a book written by Michael Pollan. PBS has created a documentary based on the book to highlight how human have artificially selected for specific traits in plants for agriculture purposes.