It is now possible to get a watermelon any time of year. Purchase a large watermelon and slice it open in front of your class. Give each child a large slice of watermelon and ask each to remove all the seeds in her slice. Pass out seed counter mats to each child. A counter mat can be a large piece of laminated paper that is divided into several sections. Each section should be able to hold five seeds. Children should place five seeds in each section. Students can then count the number of seeds in their melon.
Save the seeds from the previous activity for this tactile alphabet lesson. Using red or pink and green construction paper and a glue stick, have children create triangular watermelon slices. Give each child in the class a different letter, and have the child create the upper- and lowercase version of her letter on her watermelon slice using seeds. Glue the seeds onto the watermelon slice and display your watermelon seed alphabet in your classroom.
Bring several different-sized watermelons to class. Allow the children to study, observe and touch the melons. Ask the children which watermelon they think weighs the most and to make predictions as to how much each weighs. They can also guess the circumference of each melon. Use a small bathroom scale to measure the weight of the melons and see how close the children's guesses were. Use a piece of yarn to measure the circumference of each melon and compare the results with children's predictions.
Use the seeds from one of the other watermelon activities your class participated in to plant the seeds in a class garden. Read the book "Watermelon Day" by Kathi Appelt with your class, which is the story of a little girl who waits all summer long for the watermelon seeds she planted to grow. It is a good story to introduce the importance of taking care of a growing plant and the patience needed while waiting for it to grow.