Children have a knack for messing up anything tidy. Unlike their rooms, and the car, however, your computer can be kept orderly – at least in part. On Ubuntu, it is possible to lock down the panels (the top and bottom bars with icons and menus).
Firstly, get System Tools>Configuration Editor displaying. Do this from System>Preferences>Main Menu.
Once the menu item is available, go to System Tools>Configuration Editor>apps>panel>global>locked_down and tick it. In Karmic there appears to be no need to reboot or restart Gnome. It is not too painful to undo this, make some changes, and relock it if necessary.