I helped Robin set up for the wedding, and one of the jobs I had was to put the sodas and waters into the half barrels. Ru has recently been working on "in" and "out", and "open" and "shut". She enjoyed putting the water bottles "in" and often clapped after she achieved her goal.
She also enjoyed taking them back out of course. And when it was time to clean up and take our leftover waters home, she had a great time closing the cooler after each bottle I put in. (which didn't exactly help speed the process along, but was really cute! :)