a guy explains a formula
a man explains a math equation
a man explains the foil method for factoring polynomials
a man gives instruction on factoring polynomials at a white board
a man is doing math
a man is explaining how to do a math problem
a man is teaching a math formula on a white board
a man is teaching math in a classroom
a man is teaching math on a white board
a math tutorial session is in progress
a person talks about factoring polynomials
a teacher explaining an equation on the board
a teacher is talking about factoring polynomials
a teacher is teaching his students how about factoring polynomials
a teacher is teaching math
teacher demonstrates how to factor polynomials
teacher teaching lesson in a classroom
teacher teaching students math
the teacher taught about factoring polynomials
a man is explaining how to do a math problem