Lesson-4.markdown

@@ -9,6 +9,7 @@
 **Activity duration:** 3 hours
 
 ## Goal
+The gaol of this exercise is to make the LEGO 9797 car follow a black line and stop at the end of the line when the car drives into a goal zone - a green rectangular piece of paper at the end of the black line. The idea is that we will try to use the light sensor to detect three different colors. 
 
 ## Plan
 The plan is to follow the instructions for Lesson 4 [1].