Sorry to be a nuisance. It seems that my problem arises from the last three lines. I am not sure why.I get the message.
"Oops, try again. Did you create an instance of Triangle called my_triangle?"
I know mu code is not elegant
class Triangle(object): number_of_sides = 3 def check_angles(self, angle1, angle2, angle3, total ): self.angle1 = angle1 self.angle2 = angle2 self.angle3 = angle3 self.total =angle1+angle2+ angle3 if total==180: return true else: return false my_triangle = Triangle(35, 55, 90) print my_triangle.number_of_sides print my_triangle.check_angles(35, 55, 90)