Assuming that you mean for non-commercial purposes, then yes, all content posted on Socratic can be used free of charge as long as you respect our license.
All content posted on Socratic is under a Creative Commons-Attribution-NonCommercial-ShareAlike license
In a nutshell, that means that
"...you can share the content however you want, except you have to credit and link where you got it from and say if you changed it. You also can’t sell or make money off the content and if you adapt the content then you have to give anyone else who uses it the same rights you have.
The above is taken from Socratic's Terms of Service.
So yes, you can use our content for educational purposes as long as you follow the requirements of the license.