This is a very interesting and knowledgeable app for those who are beginners in robotics.
In this, there are many MCQs, Fill in the blanks, True & False and Fundamentals of robotics are covered.

List of topics covered are:
1. What is robot
2. Robot components
3. Actuators
4. Degree of freedom
5. Locomotion
6. Manipulation
7. Sensors
8. Cameras
9. Lasers
10. Sonars
11. Control Architecture
12. Representation