Fun Math

Teacher writes a sum, 3 + 7 = 9, on the blackboard.
Teacher: Is the sum right?
First Student: Wrong.
Second Student: Right.
First Student: Wrong.
Second Student: Right
First Student: 3 + 7 should be 10 and not 9, right?
Second Student: Right
First Student: Then why did you say 3 + 7 is 9 right?
Second Student: Because you say it is wrong and I agreed with you.

huH?
lol

The second student agrees with the 1st student by saying right, thats basically it.