Chemistry science  project   <B>Figure 1.</B> Picoboard, photoresistor, and Scratch program for this Briggs-Rauscher science project. The Scratch screen is visible on the laptop screen. To measure color changes in the reaction, a clear cup with the reactants is placed over the photoresistor and held in place with the rubber band. As the reaction proceeds, resistance changes in the photoresistor are detected by the Picoboard and transmitted to the computer, where a Scratch program stores and graphs the data.