Many children have their molars sealed to help prevent cavities. In an experiment, 120 children aged 6–8 were randomly assigned to a control group, a group in which sealant was applied and reapplied periodically for 36 months, and a group in which fluoride varnish was applied and reapplied periodically for 42 months. After 9 years, the percent of initially healthy molars with cavities was calculated for each group. Identify the experimental units and the treatments.