Glad you had a better day and I doubt it is beginners luck although having the ringleader away must have helped. Stay positive. Stop the class if they are noisy and point to the rule on the board: follow instructions, work without disturbing others. You must practise and stay positive. Give plenty of praise where it is due. Focus on what went well yesterday - you had a good day the best one so far so build on that. Try to enjoy working with the children - it isn't the end of the world if they don't behave perfectly every day. That is what I learnt after NINE years!