Khan Academy Android App Student Log in

My third graders will be using Khan Academy on Samsung tablets.  I see there are two apps to download:  Khan Academy for Kids and Khan Academy.  Which one has kid access and provides a student log in?  I have already set them up with a user name and password but cannot find where students are supposed to log in.  Can you help me?

I agree with the above comments about it being difficult to use.  If it's not teacher friendly, how is it going to be student friendly?  I've spent over an hour now downloading both apps, trying my email, etc. but no where can I find a place for students to log in.

We're not using computers.  Help!