A simple and fun project for your third grade students to participate in is a movie and book project. Have your students vote on a particular movie to watch in class that relates to a particular book. Set up the room like a movie theater. If you have the funds, order pizza and allow each student to bring her favorite bag of sweets for everyone to share. After the party, have each student to write a mini movie review.
Students can create memory booklets of their school year. See Resources to print out the booklet. Allow each student to write his memories about you as a teacher, such as favorite things you do and your worst punishment. You can also take pictures with your students to add to the memory book. Students can write and draw pictures about themselves, their favorite clothing, favorite subjects, their best friend, their funny moments in third grade and big changes that occurred in third grade.
Allow each student to dress up as the professional that he desires to be when he grows up, such as a doctor, fireman or reporter. You can provide scrapbooks and allow the students to decorate the scrapbook. The students can get pictures of their desired profession from magazines and newspapers to place them in their scrapbooks. Allow your students to uniquely create their scrapbook according to their desire.
A trip to the zoo will allow the students to get some walking exercise and to learn as they read about the different animals presented at the zoo. You can choose to watch the dolphin show, have the students pet farm animals or watch the monkeys go wild in their cages. You can also create a theme and worksheets for your students to use at the zoo. Have each student choose a favorite animal and write about what she learned according to the animal's description at the zoo.