A lot of preschool students will already be familiar with "The ABC Song" or "The Alphabet Song" (see Resources) even if they don't associate it with letters. Start by singing it in class, using a pointer to point at each letter on your wall alphabet. Hold up letter cards (use construction paper and markers to make your own) as you sing, and progress to having children hold up individual letter cards as the class sings.
Big books make the text is easy to see and help introduce letters to children in preschool. If your school does not have any big books, borrow some from your local library or purchase them from a school book fair (see Resources). Effective big books for preschool students include "Brown Bear, Brown Bear, What Do You See?" and "Eating the Alphabet: Fruits and Vegetables from A to Z." These books have predictable text and do not have an overwhelming numbers of letters on a page. Point to the text as you read so that students begin to associate letters with reading.
A letter scavenger hunt encourages preschool students to find letters in the world around them. It can be done in the classroom, on a walk around the neighborhood, or it can be done as a family activity at home. Either the teacher or the parent should write each letter after the child points to it, preferably on a large sheet of paper so students can see it easily.
Each student gets a piece of poster board or cardboard with a letter written on it. Preschool students trace the letter with a glue stick, then sprinkle on sand, glitter or attach small craft pompoms. After the projects dry, the children can trade letters and practice tracing the letters with their fingers.
Use alphabet flashcards (make your own with index cards or see Resources) to play Memory with preschool students. Lay all of the cards face down and take turns flipping two over. If they match (you can do this with exact matches, upper and lower case matches, or letter and picture matches), you keep the pair. If not, you put them back face down. Whoever has the most pairs at the end is the winner.