DS1307 Real Time Clock Breakout Board Kit is a great battery-backed real time clock (RTC) that allows your microcontroller project to keep track of time even if it is reprogrammed, or if the power is lost. DS1307 Real Time Clock Breakout Board Kit is perfect for data logging, clock-building, time stamping, timers and alarms, etc. The DS1307 is the most popular RTC, and works best with 5V-based chips such as the Arduino.
This breakout board is a kit and requires some light soldering which should only take about 15 minutes. Please check the documentation page for a list of parts and assembly instructions
Sample exercises of the functions of the clock:
https://fabienroyer.wordpress.com/2011/01/03/keeping-track-of-time-on-a-netduino-using-a-maxim-ds1307-real-time-clock/
https://www.adafruit.com/products/264