In the Android Studio go to File then Close Project. Then take the folder (in the workspace folder) of the project and copy it to a flash memory or whatever. Then when you get comfortable at home, copy this folder in the workspace folder you’ve already created, open the Android Studio and go to File then Open and import this project into your workspace.
The problem you have with this is that you’re searching for the wrong term here, because in Android, exporting a project means compiling it to .apk file (not exporting the project). Import/Export is used for the .apk management, what you need is Open/Close project, the other thing is just copy/paste.