at random

During a recent class, six of the 11 students were chosen at random to perform short sets.

The 32 seeds were joined by players ranked 33-64, and drawn at random into the left side of the draw against the remaining 64 qualifiers.

You might hear "ghost" harmonies, where backing vocals appear and disappear at random.

It is rare to find a book that you can open at random and almost always find something that piques your interest.

"Think of trees in a forest -- they grow at random positions, but not completely random because they're usually a certain distance from one another," Martiniani explains.