How can I text using my Mac without having an iPhone to Android devices? My 85 yo Mom doesn't have a cell phone but does have a Mac. My son is going to college and she wants to keep in touch but he only texts and has an Android. I think I can set-up iMessage on her Mac as she has an Apple ID, but can she send texts to Android phones?  

She also has an iPad but has trouble using it.
Why not go with Skype?

It has clients for Mac, PC, iPhone, and Android.  It even has the option to send native SMS (text) messages but there really is no need if both parties have a Skype client.

Best of all, she can message, voice and video chat.