Crossing the midline refers to one’s ability to reach across (with both arms and legs) the invisible line we could draw down the centre of the body. To be able to coordinate both sides of our body, we need to be able to cross that invisible line. Activities that encourage a child to cross the midline with his arms and legs encourage communication between the two hemispheres of the brain and develop bilateral coordination – or the ability to use both sides of the body together. Children who have difficulty crossing the midline will work the right side of the body with the right hand, and the left with the left, to avoid crossing that invisible line. This makes development of a dominant hand and academic tasks such as reading and writing very difficult. Playing sports and even playground play will also be trickier. Even the ability to dress and feed oneself requires the ability to cross the midline!