It makes us think there is new information or a follow-up question and we spend time opening the thread. Simply click on the Thank button at the bottom left-hand corner of any post you find helpful. I agree with Mike.
Symmetry comes from a Greek word meaning 'to measure together' and is widely used in the study of geometry. Mathematically, symmetry means that one shape becomes exactly like another when you move it in some way: turn, flip or slide.
Explain to the student that a line of symmetry is an imaginary line that divides a figure into two congruent parts, each of which is the mirror image of the other. Provide the student with a mirror. Have the student use the mirror to determine if a line drawn is actually a line of symmetry. Provide additional practice through a symmetry sort. Provide the student with two-dimensional figures (some with lines of symmetry and some with lines drawn that are not lines of symmetry).