I am not a fan of 6 year olds

Today was the first day that Karrie and I taught our CTR class at church. We both have been pretty excited ever since we got this calling, and I prepared the lesson and activity the night before. So we walk in and sit down next to a group of 4 boys and quickly see that they are the loudest, brattyest, and most annoying in the entire primary. So they behave the worst, and I am thinking to myself "I hope everyone knows that they were this way BEFORE I got ahold of them..." I figured I would set the standard the first day that I can be fun, but that I wont let them take advantage of us. We get into class and I keep trying to get them to quiet down and Its not happening. So I start explaining that when I am speaking they need to pay attention, and KArrie chimes in and they get a little rowdier... I lower my voice and get pissed and explain that when Karrie is talking they will listen or else I will get super pissed. I explain that I will not tolerate anyone disrespecting my little wife! They looked like I had waved a knife at them or something. The rest of the day went off alot better, but Karrie said that I had scared them too much, which was not my intention.
That wasn't the kind of first day I had hoped to have, but I think they will understand not to get too wild with us in the future. This is going to give me good practice because I fully acnowledge that I have no idea how to treat kids. I was the youngest and have never really been around children at all, so I dont know what my boundaries are. Karrie wants me to be in charge of the lessons which I dont mind.
We are years away from having any kids of our own, but I think after days like today we might be another month further... Can you feed 6 year olds sleeping pills on a weekly basis without risking brain damage?