Cover the bottom of the door with tan paper and the top with blue paper. Have half the children decorate cutout pictures of kites. Write their names on each kite and glue them on the blue paper--the "sky." Have the other half of the class decorate cutout pictures of children wearing bathing suits. Write their names on and glue to the lower half of the door--the "beach." Add pictures of towels, beach balls and clouds. Write "Life's a Beach!" on the top.
Cover the entire door in blue paper to represent the ocean. Give children coloring pages with outlines of fish. Once they decorate them, they can cut them out to get practice with scissors. Then glue a picture of each child's face onto his or her fish and attach them to the ocean. You can also use cutouts of lobsters, whales or other sea creatures. Add a headline like "We're Swimming in Fun!"
Have children make their own American flags to post on the board, either by cutting and gluing strips of red paper onto white paper, or by having them color a flag outline. Make some fireworks by cutting out starburst shapes and covering them with glitter. Add a "Happy Birthday, America!" or "Happy Fourth of July!" on top. This board ties in nicely with a simple lesson about the history of America and the flag.
Have children cut out flower petals and glue them together onto paper. Write each child's name on their flower and post them on a board with the title "Look How Fast We're Growing!" If you have a door to decorate, measure each child's height at the beginning of the summer and post their flower there. You can measure again at the end of summer to show them just how much they grew. This ties in well with a lesson plan about how plants--and people--grow.
Near the end of summer, make a "back to school" theme board to get children ready for the fall. Even though most preschools run year-round, this will help children prepare for the fall transition to school that will happen later when they enter kindergarten. Cut out some school bus shapes and put children's pictures in the windows. You can also make a picture of the school and put children in those windows. Add a caption of "It's Going to Be a Great Year!" or "Fall Into Learning!"