This test is carried out by getting the child to look at an object.
It has to be something that will hold the child's interest !!
The fixating eye is covered, and if a squint is present, the uncovered eye will move to take up fixation on the object.
If the eye moves nasally, the diagnosis is exotropia ; a temporal movement signifies an esotropia . If the eye moves down, a hypertropia is present ; conversely, an upward eye movement means hypotropia.

Have a look at the example.