Encourage the child to draw a rainbow from one line to the other. Watch that their torso stays still as their arm moves smoothly from one side of their body to the other.
For the figure 8 screening tool, make sure that the child's torso remains still and watch for rigid movements as their move their arm from one side of the body to the other.
A child who shows smooth and symmetrical movements is demonstrating positive crossing the midline behaviour. A child who shows rigid movement, or is unable to complete the activity may need additional practice with crossing the midline activities.