two legs stand.
5. hold the a-frame still, and use the pencil to mark lightly on the crossbar where the string crosses it (picture 2).
6. turn the a-frame round, so that each leg stands exactly where the other had stood.
7. make a second light mark on the crossbar where the string crosses it.
8. the two marks on the crossbar should be fairly close together. halfway between them shows where the string would cross if the a-frame were standing on exactly level ground. make a heavy pencil mark or notch the bar with a knife at this point (picture 3).
1. choose a place on the slope to begin. stand the a-frame up 