National Standards for Grade Levels 8-12
 
Which brand of shampoo is the best purchase for your money? Students are asked to make a claim based on prior knowledge. Then, they perform seven different experiments to examine the properties of six brands of shampoo. Students are guided to evaluate products using their own scientifically derived evidence and economic analysis. Scientific comparisons in this consumer science activity include pH, viscosity, percent solids, foam generation, foam retention, and ink dispersion. Students also perform a cost analysis. Detergent micelles and the hydrophobic and hydrophilic properties of cationic and anionic detergents are discussed. Allow three 45-60 minute lab periods. Designed for 24 students working in groups of four. Required, but not included: heat lamp or hot plate, stopwatch, lab glassware, and shampoo.