The diagram above illustrates the mechanism of a canal lock. It is interactive so that you can understand what needs to be done to get a boat up or down a lock.
The two columns of buttons on the right of the illustration are brighter if they can be operated (Quick hint: you can't open the gates if the sluices are open ).
The top two buttons control the boat and move it to the left or right. You can tell what the other buttons do by moving the mouse over them when they are bright.
Please let me know if it could be improved or made more child friendly (i.e. clear) in any way by mailing me.