I don't think this a grabbing opportunity or taking away the right of the other student but it is the childish nature of the students. That's what makes the classroom lively and active. In a classroom where students sit silently / quietly without any reaction and waiting for their chance, in fact is not an active classroom. An active classroom with the active participation of children / students, arouses interest in the subject among the children. Otherwise, the classroom appears to be dull.
When a particular student is asked a question and when he / she is not able to answer it rightly, then there is nothing wrong when another student proactively answers the question. This helps the other student who couldn't answer the question, to learn / know the answer as he / she keenly listens to the answer, answered by the other student.
Thanks & Regards
I am sharing here my experiecne of being a teacher. When I faced a class, I could tell if I had my students attention. I could tell if my methods of teaching were working or not. I could tell if all students could understand what was being taught. Teachers should be able to read every expresion on the sea of faces in fornt of them.
I never selected individual students to answer questions. The students always raised their hands when a question was asked. If the number of hands that went up were few it was an indication that I had perhaps failed in delivering the lesson effectively. I would redo that chapter, making it as interesting as possible.
"A love affair with knowledge will never end in heartbreak" - Michael Garrett Marino
As a student I always wanted to answer the questions put forward by teacher in the classroom.
Caution: Explosive. Handle with care.