We've done this activity, or ones similar to it, for the past several years. I give my children a noun, set a timer, and see how long it takes them to come up with an adjective for every letter of the alphabet. Here you can see where we described an athlete.
Another lesson we were working on was discovering how a Present Participle verb form (verb + ing) or Past Participle verb form (verb + ed) can be used as an adjective. For example, the exciting athlete, the kicking athlete, the opposing athlete, the determined athlete, the unsettled athlete, etc.