not homework 
just something to keep my brain busy.
currently the matrix is 31x31 boolean. (side note, inside arduino do int and boolean variables use the same amount of ram ?)
i woud like to have it bigger as this would afford me greater precision, however memory requirements quickly get too large for the atmega 328
speed is not a concern, however i am almost positive my 31x31 matrix will overflow the on board EEPROM.
i have considered just feeding a few key coordinates into the EEPROM such as locations of doors, charging station, and grid position at power off, as these could be almost as useful as storing the whole matrix, however i really would like to get the data logging down, if for nothing else than knowing how to do it for my next project.
i will give your suggestion a test,
would the same method work one of those cheap external I2C EEPROMs?
regards