forms for kids and rainwater

A few snapshots of some forms I'm playing with-

This form came to me as I was thinking about rainwater collection- there is a need for an amphitheater/storytelling place in the space- this could be such a place- I had envisioned the high sloping walls being no more than 2' tall- inviting climbing kids and making a place to recline on the backside. the sloping surface is grass, and gathers at the center- a decorative inlet at that place could provide a visual celebration of the collection of water, as well as a place to stand if you're telling a story...

These are both quick studies of ramps to climb - I envisioned these being for the kids- a place to get above the normal eye level and view the world. the lower one is pretty exaggerated... how to do either of these without obnoxious railings? total height- maybe 3'.
10' diameter? maybe this could be worked into the sloping amphitheater- another way to get to the top of the grassy peak.