Data logging is the collection, collation and displaying of information gathered with the help of special sensors which are attached to a computer. These sensors could be specialised thermometers, light meters or even microphones. They could be used to measure the differing characteristics of any chosen environment, or the changing conditions during an on-going experiment. In the primary school this could be from an investigation in the classroom, or better still from an ecological project carried out in the field. Although a number of different types of sensor are available, it is sensors which log temperature, light and sound that are most commonly found within the primary school.