Grove - Temperature Sensor uses a thermistor to measure ambient temperature. The resistance of thermistor changes based on ambient temperature. This resistance value alters the output of a voltage divider which is measured by an analog input pin and converted to a temperature value. The operating range is -40 to 125°C , with an accuracy of 1.5°C .For all Grove users (especially beginners), we provide you guidance PDF documents. Please download and read through Preface - Getting Started and Introduction to Grove before your using of the product.