A Letter a Day
Pick a "letter of the day" and have the child be on the lookout for that letter. The child can write down words that come up during the day that start with that letter, like foods from a meal, toys, plants or animals you see on a walk, and so on. If you have access to magazines or newspapers, have the child cut out a few words that start with the letter, or pictures of things that start with that letter.
