A new type of ammeter (PikoPikoII) has been developed which indicates the measured current by the movement of a spot of light and the voltage by the colour of the spot. Since this tool can make students feel as if they are observing a visual image of electricity, it is easy to prepare schematic explanations on electric circuits that match the students' observations using the PikoPikoII. From such a viewpoint we used a restaurant model with a PikoPikoII in a trial lesson for junior high school students, and found that such a combination is much more helpful to them than explanations using ordinary fluid-flow models.