A cellphone-based math tutor is no substitute for a real teacher – but for some South African students, Dr. Math is all they've got. Dr. Math is a program linking high-school students with volunteer ...

In the millions of messages that flit through the ether on Mxit every day, a call for help breaks through, thumbed in a rat-tat-tat of half-formed words and digits adrift at sea. "Okay," runs the ...