Remind101 is a communication tool using the technology everyone is carrying in their pockets, their cellphones. And as a teacher this communication is one-way, which means those receiving your text messages can't reply back.
Start by creating a free account at Remind101. After you have signed in you create a class then invite your end users to sign up. End users sign up procedure is completed by having them send a text to a phone number with the body of the message containing a particular code correlating to the class you created. If they enter it all in correctly, Remind101 replies back asking for further information from the end user and they are then part of your class.
To send everyone in your class a text message, you go into Remind101, type in the message, and click send. You can even schedule it to send later. There is even an option to have a Remind101 widget scrolling on your blog or website.
This is a great tool for elementary teachers to have parents of students sign up so they can be reminded of particular events; for instance a field trip tomorrow so please pack a sack lunch, or conferences next week. High School teachers can have their students sign up into particular classes so they can remind them of due dates for projects, to study for a test, or even offer problems to solve.
For the people carrying tech tools in their pockets, Remind101 does provide access via iPad or iPod apps, as well as Android or Google Play Apps.