This kit is designed to have the 4x7 segment display which displays the temperature mounted directly on the Arduino board. The 3-pin wire leads connect a thermistor to an analog pin on the Arduino. Once the Arduino is programmed, a 9-volt battery can supply the power. The thermistor can be replaced with other types of sensors and the Arduino can be reprogrammed to display those sensor value readings.
(This project is based on a display that is not available at Jameco. You will need to purchase the 4x7 display (COM-09482) from SparkFun.)