Through the step by step animation, students would be able to see how an experiment provided evidence showing that a gene is made of DNA. Previous studies from Griffith "showed that a harmless strain of bacteria can become infectious when mixed with a virulent strain of bacteria that had been killed. The dead bacteria apparently provide some chemical that transforms the harmless bacteria to infectious ones." No one at that time knew what this "transforming chemical", or so-called a gene, was made of. This site uses detail animation to demonstrate the classical experiment conducted by Oswald Avery that provided evidence showing that genetic molecule is DNA, not protein. In this experiment, two strains of Pneumococcus bacteria (R strain and S strain), which cause pneumonia, were used to infect mice. Instructors may use this site as a class inquiry activity. Instructors can ask students to propose some explanations for the myth: why inactivated S strain still cause mice death after mixing with R strain. The step-by-step animation may help students understand how DNA was proved to be the transforming molecule. I suggest instructors not show the following steps immediately, but first let students come up with what to do in the next step. Students should do the "problem" to test if they understand the basic principle. The problem contains three multiple choices. The website not only has animation, but also concept, gallery, audio/video, bio, problem for students, and links. This site is one of the chapter out of the 41 chapters under the project "DNA from the Beginning", which is an animated primer on the basics of DNA, genes, and heredity.