How to make the most of a bad situation

My trouble student’s father was late picking him up again today (15 minutes!). Luckily, or unluckily depending on how you look at it, I have several new students starting next week, so I will not be able to baby-sit this student if his dad is late again. After visiting with the cat, we got our shoes on, and I said come look at my flower garden outside. I introduced him to lavender, and it was actually quite endearing how he responded. I showed him how to gently rub the flower between his fingers and smell them. He said, Coool! I said, “That’s called lavender,” and he said, “I’ve heard of lavender before. That’s neat.” Honestly, I would have expected him, or any other kid for that matter, to shrug. I then pointed to a sprig growing next to it and said, “That, however, is a weed; let’s pull it out.” We did, or rather, I did, then I said, “Can you find any other weeds?” Now, is it immoral of me to have put my student to work weeding my garden and front lawn? It was only a couple more minutes until his dad arrived, but I was starting to see value in his tardiness.