They grow up so fast

Our eldest daughter was complaining today about doing her Math. Months ago, we had taken all the kids' Nintendo DS systems with the understanding that they needed to finish their Math books to get them back. At this point our eldest had only two pages left in her book, but was still in tears on sitting down and finishing it.
Well today we received a few boxes of Lego robotics, and extra parts for the upcoming FLL (First Lego League) Robotics competitions. (I will post on this later; our older two are both in FLL this year.) All three kids were very excited about opening the boxes, but they were told they had to do their math before opening the boxes. You would of thought we asked the eldest to kill her cat.
Long story short, eight hours latter, (not exaggerating) things had settled down. Most of the Math was done, tears were dried and everyone was getting ready for bed. Our eldest comes down and asks:
"When I finish my Math book tomorrow, can we open the Lego boxes?"
"Yes, after your Math is done."
"What else do I get when I get when I finish my book?" she asked.
"What do you mean?"
"What else do I get for finishing?"
"Knowledge."
"What else?"
"We stop yelling at you."
"No Dad, what do I get?"
"What are you talking about?"
"What else?"
"I have no idea what you are talking about." After this goes on for a few more minutes, I finally got it.
"I now know you are growing into a woman; you are speaking in hints. If you want to ask for something, just ask for it."
She finally got to the point and said in an exaggerated voice, "Can I have my DS back after I am done with my Math book?"
I said what any good dad would say. "No, go to bed."