You can find more information on the Vestibular and Proprioceptive senses in our book A Moving Child Is a Learning Child by Free Spirit Publishing.
Lay out a plank several inches off the ground, threading one or more hoops through the plank. (See photograph). Encourage the child to crawl across the plank. Each time he reaches the hoop, encourage him to crawl through the hoop while maintain his balance on the plank. As the child gains confidence, suggest trying to walk across the plank, crawling through the hoops as he goes.