Start from an interactive
One of the ten interactives could be used as a stimulus to discover more about the nature of the technique that lies behind the interactive and more about the nature of DNA and genes.
Example
The students work through the genetic fingerprinting interactive (DNA profiling). Students could then be encouraged to develop their own set of questions about the process and the materials used in the process or the teacher could lead the discussion and investigation by asking:
What is DNA?
How has it been treated in this process called electrophoresis?
How are restriction enzymes involved?
Why do the results for different people show different patterns?
What is the relationship between different genetic codes, different genes and different characteristics in people?
Background reference material and other support materials can help exploration of these questions.