If you’re teaching over the summer months, you may want to use the season’s unique activities and events to develop lessons.  Check out the ideas available at the following sites.

Activities for Summer School ESL

AMC Montessori Summer

Sand Castle Tips and Tricks

Sands of the World
Interesting, but sophisticated -- a good compare and contrast activity

Summer Fun Lesson Plans and Activities
An interesting collection of ideas for summer learning -- the month without holidays lesson is especially good.

Summer Fun Monthly Calendar
Very large link site

Summer Season Preschool Activities and Crafts

Summer Theme Lesson Plans
Plentiful, but very uneven -- these are mainly for primary levels.