How to install Gnome Shell so you can use Gnome Classic instead of Unity
Here’s how you can use Gnome Classic instead of Unity in Ubuntu 12.04:
1. Launch Synaptic.
2. Type in “gnome shell” without the quotes into the search box.
3. When you find Gnome Shell, right click, then click the Install button.
4. After the install is complete, logout out of Ubuntu 12.04.
5. Choose Gnome Classic from the login screen and you’ll use that instead of Unity for your desktop environment in Ubuntu 12.04.