I need some leadership advice

Before you teach, plan plan plan. What are the things that might go wrong? What might children not understand? Have answers to all these questions before you start teaching.

Then, when you are in the classroom don't even think about trying to explain anything until all the children are quiet and actively listening to you. If it takes 5 minutes to get silence then so be it, but there is no point in doing anything if they are not listening.

Finally, break your activity up into 5-10 minute chunks with opportunities for everyone to stop, question what has just happened and provide details about the next step.

Good luck!