[Grammar] How to write this sentence correctly?

[rukmini]

The teacher had to read the assignment again for the students,since they had difficulty understanding what to do after he had explained it the first time.

 

[Allen165]

NOT A TEACHER.

I don't think "read" makes sense; perhaps you meant to write "read out."

 

[Allen165]

"Read the assignment again" is fine if that is what the teacher did - the teacher stood in front of the students and read the assignment to the students.

Another term that could be used is "explain" - the teacher told, in detail, what the assignment was.

You also use, "go over" - the teacher had to go over (explain again) the assignment again - the teacher spoke to the students and told them what they had to do.

I think if you want to keep "read," you have to make minor changes:

"The teacher had to read the assignment to the students again because they...."