As I thought about the #mathphotoaday project the rest of the day I realized that the concept applies to other areas too. The idea of a photo a day project is to have students take and share one picture per day for a month about ideas related to a topic. The #mathphotoaday project asked kids to take pictures that demonstrated math concepts. You could do the same with topics in science, social studies, and language arts too. In science you might have them take pictures about phases of the moon or changes in seasons. In social studies you might ask students to take pictures about government in action. And in language arts students could take pictures representative of new vocabulary words they're learning.
Sharing the pictures in a photo a day project could be done in a variety of ways. Depending upon the age of your students and your school's policies you might have students use a hashtag and share pictures on Instagram or Twitter. You could also have them share pictures on a group blog. A moderated Padlet wall is another option for sharing images.