Though the publisher designated this unit for use with third through eighth grades, this particular lesson would be best used with middle schoolers due to the specific measurement skills required. Basically, they set up the reaction between vinegar and baking soda, but add detergent to make the gas bubbles last longer. The amounts are varied and resulting suds column heights are compared to demonstrate that reactant amount affects product amount. Consider introducing the terms reactant and product since learners will likely use them in future chemistry courses.