Hmmm. маме is dative and not accusative because помогать commands dative. We have to just learn this feature for each verb, analogous to learning genders of nouns, I guess...
What's the difference between "Завтра мы будем помогать маме" and "Завтра мы поможем маме"?
Эти два предложения одинаковы по смыслу. Но, если вы скажите "Завтра мы целый день будем помогать маме.", то в этом предложении нельзя использовать "поможем".
The difference is the same as between “I will be doing something tomorrow” and “I will do something tomorrow”.
and what is the difference? In German you both translate as " Ich werde morgen etwas tun"
Tomorrow we will help our mom. I really don't understand why it is incorrect.
Pronunciation on the audio of маме is dreadful
I gave "Tomorrow we will be helping mama" and it was rejected.
"Mum", "Mam", "Mummy", and "Mama" are all used in British English, but not "Mom". Elsewhere Duolingo accepts "Mama" but not on this one.
What is wrong with "tomorrow we shall help mum"?
"We will be helping mother" is wrong. A/the/our etc. is needed.
Not really. Lots of people refer to their mother as "mother". And that's the meaning of "мама", this isn't just some generic "mother".
Вы забыли слово "Tomorrow"
Bad idea to say that something is wrong without being absolutely sure. It backfires easily (-3).