In this week’s lesson, I continued the theme of how data is stored in computers, this week focusing on binary addition.
Lesson 1: Theory (Binary Addition)
Suggested time: 50 mins
I started with a fun starter activity courtesy of Mark Ward via CAS called Binary Bingo. To download the activity, click here.
Each student was given a bingo card and numbers were picked at random using a free random name selector (see Classroom Management Tools). The first student to get a full house was the winner.
I began by writing a simple sum (adding to denary numbers together) on the board:
I then asked for a volunteer to solve it (showing all working out).
Next, I introduced a simple binary sum:
I explained that adding binary numbers is exactly the same as adding denary numbers however, instead of carrying groups of ten, you carry groups of 2. I followed this by writing a couple more simple binary sums on the board and asked for volunteers to attempt to solve these.
Next I explained that when we add two 1s we need to carry over to the next column. I demonstrated this using the following sum:
I followed this by asking students to work out the following (explaining their working out):
Finally, I wrote the following binary sum on the board and asked the students to solve it. I then asked the students if they spotted the problem.
I explained that, if we only have 4 bits to store the result, there would be no room for the final carry – resulting in the wrong answer. I explained that when there isn’t room to store the resulting calculation, we get an error which we call overflow.
Finally, I gave students a series of binary addition challenges courtesy of Chris Barnard via CAS. You can download the worksheet and answer sheet here: Binary Addition Exercise
Students were directed to the following YouTube video explaining binary subtraction:
Students played the CISCO Binary Game: http://forums.cisco.com/CertCom/game/binary_game_page.htm
Binary Calculator – http://gwydir.demon.co.uk/jo/numbers/binary/add.htm
Binary Arithmetic Task - http://www.allaboutcircuits.com/worksheets/bin_math.html
Lesson 2: Raspberry Pi - Python Challenge
Suggested time: 50 mins
Students were instructed to setup their Raspberry Pis and to launch IDLE 3.
Students were then asked to attempt a series of introductory Python challenges courtesy of Tom Gilmour via CAS: http://community.computingatschool.org.uk/resources/332
Alternatively, if you do not have access to a set of Raspberry Pis, students can still complete the Python challenges:
To install Python for FREE, go to the python.org website and download a standard installation of the latest version of Python. This will provide you with everything you need.
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