"My mother has blue eyes."
Translation:Moje matka má modré oči.
Since "oko" is neuter, why wasn't my answer ending with "modrá oči" accepted?
No, we distinguish the more formal forms: father, mother, otec, matka and the more informal ones: dad, mum, daddy, mummy, táta, taťka, tatínek, mamka, maminka,...
You are right. Still maminka is not wrong. My czech teacher perfers maminka to matka.
She is using maminka and not mother in her classes. She prefers the more informal form. I think if both forms are correct they should be given as options but hey, it is your site - you know better :)
It certainly not my site nor the site of the contributor team. The decision to srparate them was made by several people after a careful consideration of the advantages and disadvantages.
What your teacher prefers is also a possible approach. Sometimes one must decide between several possible approaches.