Hello All, My daughter, Natasha, is in 4th grade. She had the following homework question about rays that confused us: Name as many rays as you can in the figure below. <---.----.--------------------------.-----.------.------> (line not dotted on homework sheet)       L   M                              N     O      P She named: --> --> --> --> --> -->  --> --> -->  --> -->  --> -->  --> -->  --> --> --> -->  --> LM, LN, LO, LP, ML, MN, MO, MP, NL, NM, NO, NP, OP, ON, OM, OL, PO, PN, PM, PL In grading the answer all of the above were crossed out as incorrect except: --> --> --> -->  --> --> --> LP, ML, MP, NL, NP, OP, OL                                           -->                                                       --> We can see that, for example, LN (one of those crossed out) is included in LP, but does that mean that there is not a ray            --> named LN? Thanks so much for your help! Natasha, 4th grade and mom Hi, In geometry a ray or half line starts at a point and go indefinitely in some direction. The term probably comes from a light ray. To specify a ray you need two points, a starting point and a second point to indicate the direction. In your example above --> LN is the ray that starts at L and goes to the right. The ray --> LP also starts at L and goes to the right. They are exactly the same ray, they are just described differently. In the problem you were given here you can describe 4 rays that go to the right, one starts at L, the second at M, the third at N and the fourth at O. There is a ray that starts at P and goes to the right but you have no point to the right of P to allow you to specify "to the right". There are also 4 rays you can describe that go to the left. What I don't understand is that in the answer given there is no ray that starts at P and goes to the left. You might call it --> PO or --> PN or --> PM or --> PL but it should be there. I hope this helps, Penny