I have been learning the verb list for the N4 exam but I do not know how to tell the group of a verb. Until now I have memorized them by heart. Nevertheless I still have trouble telling the group of a verb because I can't memorize them all. I wondered whether there is a systematic method of knowing the group of a verb. Could you help me with that?

According to my textbook:

* いきます belongs to group I
* ねます  belongs to group II
* きます belongs to group III