$ sudo apt-get update
$ sudo apt-get install ldm-edubuntu-theme 

ldm-edubuntu-theme is installed in your system.

Make ensure the ldm-edubuntu-theme package were installed using the commands given below,

$ sudo dpkg-query -l | grep ldm-edubuntu-theme *

You will get with ldm-edubuntu-theme package name, version, architecture and description in a table

ldm-edubuntu-theme package basic information: