I assign this to my Digital Photography students as a "Photo Journal". These pictures are meant to give the students the same freedom they have when snapping pictures on their cell phones as they already do, but gives them more direction and motivation.
The students are to email the photos or put them on dropbox (instructions can be modified for your class settings) every Monday, giving them the weekend to take the photo. They are welcome to use and experiment with any photo app available to them.
My students really enjoyed these and it seemed they enjoyed the challenge and excitement of photographing more than just "selfie's"! I hope you and your students enjoy the results as much as I do!