The Remind app is a great one for communicating those simple messages.
I also used the app to update parents on our ETA coming back from a field trip to the state capitol, as well as taking a picture of my assignment board everyday. Many parents would tell me how much they appreciated the daily remind text message as they would know what was going on at school before their child would even come home.
While it is great for the classroom teachers out there, it is also great for after school activities, clubs, etc.
Remind has added new features such as the ability to create a group (such as parent volunteers for a classroom party) and send them a message, as well as the ability to send a private message. This is all done without anyone knowing each other's phone numbers.
To see a video - click on this link and then watch the 1 minute video explaining how the site works.
Should you have any questions, please send me a message through Facebook, or comment below.