You would life to perform an experiment the effectiveness of extra-fluoride toothpaste on students aged 5-14 who have early-stage tooth decay. Assume the extra fluoride toothpaste has already been proven to be safe for children to use.

You select a random sample of twenty students aged 5-9 and thirty students aged 10-14. Describe a randomized block design [blocked by age group] you will use to test the effectiveness of the extra-fluoride toothpaste.

Remember to detail the key elements of your design concerning control and randomization. List the response variable you will use to collect your data as well as at least one possible confounding or lurking variable.