Introducing Computer Science to lower secondary pupils: the seven-segment display

Today was my first day teaching at a morning lower secondary school (I've been teaching to adults in secondary for 7 years). Naturally I wanted to introduce myself and break the ice, turned out I already knew some of the pupils or they knew me so we spent five minutes on casual chit-chat then I told them we had to get down to business. They weren't really thrilled about the option of opening their textbooks, so I told them: "Let's play a game instead". I drew a digital 8 on the board and asked them what it was. "8" some said, "electronic 8" said another, "digital 8"! "Perfect! " I said and continued: "Have you ever wondered how the digital display of a watch works? Hear me, this is University stuff here: I was taught this in Electrical Engineering!" They caught on right away.

I told them that the "8" I had drawn on the board was called the "seven-segment display. Count the segments and see for yourself!" I then named each segment with a letter from the English alphabet and proceeded to draw a table with the ten digits of the decimal system as rows and the letters a-g as columns. The idea is that when a segment is ON, the value in the cell of the table is "1". When a segment is OFF, the value is "0". I then asked who wanted to come to the board and fill in the cells for the decimal digit "0". I covered the middle segment with my hand as a hint, all of them raised their hand and the pupil I chose entered 1-1-1-1-1-1-0 in the row. Excellent! Now all of them wanted to give it a try: 1 was easy, 2 was a bit tricky so I drew a digital 2 on the board and they got it, 3, 4, the pupil doing 5 was having a hard time so I told him "just put "1" in the cells that are ON and then fill in the zeros". He managed, 7 was fine (I explained that a universal 7 doesn't have the little horizontal line in the middle like they learn in Greece, but they had all seen digital sevens and already knew that). I called the pupil who was having trouble with the 5 to do the 8 as a "giveaway". After 9 was on the board I told them that they had just grasped the concept of how ALL information can be coded into digital functions. OK, I couldn't go any further than that - not that they would have much difficulty in understanding the fundamentals of Boolean Algebra or Switching Theory, just that we would be getting WAY off track! - but I think I made my point. When the bell rang they didn't want to leave! So I told them next chapter is about computer hardware and promised "open-heart surgery" on a "deceased" computer...:-)

I took a picture of the whiteboard with my cellphone:)

 Note: The wonderful world of digital technology all around us is the #1 testimony to Computer Science as exactly what it is: A SCIENCE. In most countries this is self-evident and needs no further explanation... Not in Greece. Computer Science teachers struggled to show the Greek Ministry of Education as well as European Union education agencies how eliminating SCIENCE from Computer classes in Greek secondary education and downgrading to merely learning computer skills would be detrimental to the "added value" offered to pupils by studying Computer Science. Unfortunately the law bill for the "New Lyceum" is now a law, and "Computer Programming" is no longer in the curriculum for University Entry Exams: those pupils wishing to pursue Computer Science degrees in Tertiary Education just don't have the option of studying Programming in High School like they did for the past 15 years. Instead, they have to attend Chemistry classes. Chemistry is fine, but a computer-technology oriented curriculum is far more appropriate for those students who are determined to pursue a career in Computer Science. It was an exemplary practice that was successfully in place for 15 entire years in Greek education, and it was torn down in one night in late August. The Minister still hasn't provided an answer to the question asked by bewildered Computer Science teachers and students: WHY??? It's a giant step backward, as noted by the Executive Director of the Computer Science Teachers' Association in the CSTA blog post on 26 Aug. 2013. Greek CS teachers have not surrendered: by channeling all our creativity and passion for what we do, we're proving in the classroom what the Ministry refuses to see. And there are many on our side: students, parents, University professors, entrepreneurs... the Ministry may be blind to the future, society is not.