Only if it was the subject. The word "discipulos" is accusative. It cannot be the subject of any sentence.
In Latin, the verb must agree in (person and) number with the subject. The object can be of any person or number without affecting the form of the verb.
In Duolingo, as in real life, you have to use your knowledge of possible sentences to interpret what you think you're hearing. It's just that, in your native language, you do this automatically, without noticing.