There are a few reasons why skiers zigzag when they ski. One reason is that it helps them to control their speed. By zigzagging back and forth, skiers can slow down or speed up as needed. Another reason is that it helps skiers stay balanced. When skiing down a hill, for example, skiers may need to zigzag to keep from falling over. Finally, zigzagging can help skiers avoid obstacles in their path. By zigzagging, skiers can more easily avoid tree branches, rocks, and other objects that might otherwise trip them up.