A typical problem in modern robotics education is to build a line following robot. This is a device which can track a line on the ground with the help of a sensor. The easiest form of programming is an if-then-statement:
if line_is_left then move_left
if line_is_right then move_right
In most cases, learning by doing has the top priority. The line following problem is used to get familiar with the hardware, software and with the project group. It's a task which is repeated by all newbies to learn the basics.
Perhaps some words to the references at the end. Both are external links to youtube which are showing a small video. According to the search filter, both videos have a creative commons license, If they really do is unclear, but the search engine is telling so. The first link was generated by pressing the share button of the video. It is called a sharable link.
In the second video (a different line follower robot), the normal videolink was taken which is shown in the browser window.
 Omer Al-Attass: line-follower sensor, https://youtu.be/_eYy_OLNokM
 Tano: D2-1 Line following robot, https://www.youtube.com/watch?v=cP-nj7a4SEo