When John needs a dose of something and you don't know what, give him something to push, pull, lift or carry. Each one of these vigorous actions develops and enhances his proprioception… and it feels good.
When offering Jaimy both your hands, you are encouraging his bilateral coordination. Any time you encourage bilateral coordination, you are encouraging binocularity.
When handing something to Sandra, or when taking something from her, always be sure that she looks at your hand. Encouraging her to look at what she is doing teaches her to use her eyes to direct her movements, while simultaneously improving her tracking skills.