Offer healthy fruit choices to the preschool children during snack time. Prepare individual sandwich bags with a variety of fruits. If you use fresh fruit, use only fruit that is easy to eat without much mess, such as grapes. You may also want to use dried fruit, such as banana chips and raisins. Ask the children to name the fruit in the bags before they eat the fruit.
Ask the children to draw pictures of their favorite fruit. At the end of the week, invite parents and other relatives to a special showcasing of the pictures.
Use the child's senses of taste and smell. Blindfold one of the preschool children and gather the others around. Have everyone be quiet for a minute, and give the blindfolded child a piece of fruit. Ask him or her how the piece of fruit smells and tastes, and then ask the child to guess what the fruit is.
Create a fruit-themed alphabet with the preschool children. Ask them to name a fruit for each letter of the alphabet -- A is for apple and B is for banana, for example. Let the children choose what fruits the other letters stand for.
Count the seeds inside a specific fruit. Peel an orange and count the number of seeds within that orange. Next, slice an apple in half and count the number of seeds within that apple. Repeat with any other fruit that you want. This activity will teach preschoolers about fruit and basic number counting.
Read a picture book to your preschool children that involves fruit as its main subject. Ask the school librarian for recommendations. For example, "Blueberries for Sal" by Robert McCloskey is a Caldecott Honor awarded picture book that's perfect for teaching children about blueberries.