It was, over the weekend (and with their mother's supervision) installing a pull up bar in the yard, anchored in two 5 gallon buckets of Quikrete.
Precisely where I need to back our tin boat this week...
So today they got to dig it up, refill the holes, and learn about selecting an appropriate location before permanently installing something. Lots of good instruction in the use of spades, sledgehammers, pick axes, and maximum effort.