Transistors and logic probe and me

so for last class meeting we learned about transistors and how to use them in our breadboards
what transistors do is that they control the flow of electricity so to understand them better we created the following board

the LED is receiving voltage from two path but first path is blocked by the transistor but when the button is pushed it tells the transistor to let the current pass and then the LED lights
After this we incorporated the same idea again but instead of a switch we used our finger tips to allow the transistor's base pin to let the current pass through the collector and emitting pins

the next mission was to built our own logic probe which one of the most useful troubleshooting devices like a multimeter.
since i ran a little bit of time even though i finished my logic probe i did not take a picture from it but the next class meeting i will take a picture and post for all of u my devoted fans :D