Why Present Continouos instead Present Indefinite?
In my Grammar taskbook I have a task to wright down the correct form of verbs in the brackets.
"- Can you ride a bicycle? - No, but I _____(learn). My brother ______(teach) me."
Firstly I put the verbs at Present Indefinite, see below:
"- Can you ride a bicycle? - No, but I learn. My brother teaches me."
But according of keys to this exercise it shoud be done like below:
"- Can you ride a bicycle? - No, but I'm learning. My brother is teaching me."
My thoughts is that the action is not happening at the present moment, most probably it's a repeated customary action. So, according the rule of my Crammar book when it's using repeated customary action it should be use Present Indefinite. Can somebody explain me, why in this case we use Present Continouos?

Question

Why  Present Continouos instead Present Indefinite?
In my Grammar taskbook I have a task to wright down the correct form of verbs in the brackets.
"- Can you ride a bicycle? - No, but I _____(learn). My brother ______(teach) me."
Firstly I put the verbs at Present Indefinite, see below:
"- Can you ride a bicycle? - No, but I learn. My brother teaches me."
But according of keys to this exercise it shoud be done like below: 
"- Can you ride a bicycle? - No, but I'm learning. My brother is teaching me."
My thoughts is that the action is not happening at the present moment, most probably it's a repeated customary action. So, according the rule of my Crammar book when it's using repeated customary action it should be use Present Indefinite. Can somebody explain me, why in this case we use Present Continouos?

Answer

The word "learning" is used because the person is in the process of learning.  This does not mean that the person is practicing riding the bicycle at that very moment, but that the person has started the process of learning to ride the bicycle, but that he has not fully learned it yet.  Learning is more of a process that a specific action.  You could say  "I will learn," or "I have learned," or "I am learning," but not "I learn."
I hope this helps.

Answer

Это действие, происходящее near now (началось до "сейчас", закончится после).
Часто употребляется с глаголом learn.
Смысл в том, что научиться/научить что-то делать это не повторяющиеся периодически от начала до конца действия (что обозначается Present Simple), а процесс, который начался, но еще не закончился.
Человек не начинает каждый день учиться с того, с чего он начал в первый день. Он продвигается от "совсем не умел" к "научился, как надо". В то время как "обычные, привычные, повторяющиеся действия каждый раз происходят от начала и до конца (Каждый день я умываюсь, одеваюсь, завтракаю - типичный Present Simple, все действия каждый раз выполняются полностью и эти полные действия повторяются с какой-то периодичностью)

Answer

The present continuous can be used for verbs in the near future, as well as now.