Over the two weeks of the 2010 Edinburgh International Science Festival, 1300 children were entertained and educated by six Scottish MRC Units' activities making cells, viruses, DNA bracelets and test-tube babies, and testing how body symmetry correlates with response times. Protein Phosphorylation is challenging to convey to 5 to 12-year-olds, but our Unit rose to the occasion with The Cell Signalling Challenge, a puzzle representing how the pancreas signals to our muscles "Get ready sugar is coming", and how insulin and exercise help get the signal through in people with diabetes. Thanks to our students and postdocs for their enthusiastic participation. We all enjoyed the light bulb moments when children 'got it', and were surprised at how many people have diabetic dogs.