The Skills of Summer
If you have fond memories of the rhymes you repeated while jumping rope as a kid, teach them to your child as early as you like. Just don't expect her to jump rope while she sings them until she's in grade school.
Focus on the joy of jumping. Summer days spent jumping in place, jumping to music, jumping from one place to another, are the best preparation for finally adding a rope to the mix.
You can play jumping games -- jump over cracks in the sidewalk, or into a puddle, and while swinging scarves in your arms (mimicking the jump-rope motion).
As kids get older, you can put the rope on the ground and have them jump over it. You can then raise it a very small amount if they're really good jumpers, but you don't want to trip them.
Age you can expect her to...
Jump up and down with two feet: 2 1/2
Jump from one place to another: 3
Jump rope: 5 or 6
Blowing soap bubbles
It's hard to believe, but forcing air out of your mouth and through a soap-film-filled ring is quite complex. Even when your child figures out the pursed lips and gentle airflow required, the simple act of aiming a puff of air is likely to elude him for some time. Most kids aren't able to do it until at least age 3.
Don't just put dish soap in water. Most store-bought bubble liquid is reasonably good, or go ahead and make your own (you can find a great recipe, and tips, at exploratorium.edu
Try alternative wands. Those tiny little wands that come with bubble liquid get slippery, fall into the jar, and are hard for little hands to handle. An empty plastic strawberry or cherry-tomato basket is a great bubble maker for little kids -- they can dip it in a bowl of bubble solution and wave it through the air.
Age you can expect him to...
Make bubbles by waving a wand: 1 and up
Blow bubbles with a wand: 3 and up