Prepare a soap bubble solution (store-bought or homemade from dish soap and water) and take your child to the garden or balcony. Have them hold the wand near their mouth and blow gently —not a sudden hard puff— to form bubbles.
Watch how they control their breath: blowing too hard pops the bubble instantly, and too soft makes nothing at all. That balance is the whole point of the exercise. Later, vary it by trying to inflate an empty balloon (with your help at first), or a challenge for who can release the most bubbles in one minute.
This exercise strengthens the mouth and cheek muscles later used for clear speech, regulates breathing, and gives your child genuine sensory and visual delight.