To keep track of your apps you can make folders, e.g. for every subject.

If you press and hold one of the apps they all start to shake. Now you can drag one app on top of another. Those two will be in the same folder which you can give a name now. Other apps can be added by dragging them on top of the particular folder.

While your apps are shaking you can also rearrange their order, delete them by pressing the ‘x’ in the corner and move them to a different homescreen. Press the home button when you are done.