Make sure you have a good secure place to put that static camera so no one will fall over it. Make sure it is plugged into the mains power supply and use gaffa tape to stick cables to the floor. Let it run from start to finish so you have a complete audio track and use your mobile camera to get your close ups, cutaways and reaction shots of the mum's and dad's in the audience. What are you like for lighting? Is there a PA system? I'm not an audio expert but maybe someone who is could give you some pointers on taking a feed from an audio mixing desk. Make sure you get a few establishing shots of the outside of the building aswell including a name plaque or whatever. Get people arriving and going in and if possible preparing (arrive early to do this). How many sets of batteries have you got? You'll need a few sets and bring a charger with you aswell and plenty of tapes.

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Better than a poke in the eye with a pointy stick any day...