In this week’s lesson, I introduced my students to Hexadecimal - explaining why it’s used and how to convert to binary / denary and back again. Learning Objectives:- Convert positive denary integers (0
**‐**255) into 2**‐**digit hexadecimal numbers and vice versa - Convert between binary and hexadecimal equivalents of the same number
- Explain the use of hexadecimal numbers to represent binary numbers
Lesson 1: Theory (Hexadecimal)Suggested time: 50 minsStarter:I started by showing two numbers on the board (one in binary and one in hex). 1101 1001 C9 I then asked the students, “Which is easiest to remember?” I explained to students that we often find it difficult to remember long sequences of numbers so, to make life easier, we can break the number down from 4 bits (a nibble) to 1-bit. Demonstration (Hexadecimal):Next, I explained that the smallest value we can have in 4-bits (nibble) is 0000 (0 in denary) and the largest value is 1111 (15 in denary) and that we needed to represent each value with a single digit. I then displayed the following table on the whiteboard and asked students to fill in boxes 0-9:
I then explained that when we reach 10, we hit a problem as we can only use the numerical values 0 – 9. I then asked the students to suggest ways we would represent the last 6 numbers without using numbers. I then explained that, to get around this problem, we substitute the numbers 10 to 15 with the letters A to F. I explained that we call this system Hexadecimal (or Hex for short). I followed this by showing the students the following table:
Next, I showed the students, using the following table, what happens when we get to the number 16:
I explained that when we get to 16, a 1 is added to the front of the next number (highlighting the similarity to the denary system when we go from 9 to 10). Next, I split the class into groups of three and gave each group a copy of the following table. I then asked them to fill in the blanks:
I finished by displaying the following table on the board and explained how it could help them in their exam:
Activity 1 (Denary <--> Hex):Next I explained that, for the exam, students are expected to be able to convert binary to hexadecimal. I then showed the students the following video: I then showed them an example exam question and challenged them solve it: (a) Convert the hexadecimal number 6A to denary. (You must show your working out). ................................................................................................................................. ................................................................................................................................. ............................................................................................................................ (2) I followed this by giving students a series of mini challenges (See answer sheet at bottom of this page):
Activity 2 (Binary <--> Hex):Finally I explained that, also for the exam, students are expected to be able to convert binary to hexadecimal. I explained that, in the exam, students are expected to be able to convert 8-bit binary numbers to hex. I then demonstrated how to do this using the following example: This was supported by the following help sheet:
I then showed the students another example exam question and challenged them solve it: (a) Convert the binary number 00111101 to hexadecimal. ................................................................................................................................. ................................................................................................................................. ............................................................................................................................ (2) Plenary:I finished by putting this all into context. I displayed the following table on the board and asked students if they recognised it. I then asked if they spotted anything familiar (based on the lesson). I explained that #FFFFFF = 1111 1111 1111 1111 1111 1111 in Binary which is 16,777,215 in Denary which also happens to be the same number of colours in a web palette! I then asked students to think what it would be like to have to use binary to change the colour of a webpage in HTML! Homework:Students were instructed to update their class revision wiki. Answer Sheets: Starter:
Activity 1:
Useful Links: How to do Decimal to Hexadecimal Conversion How to do Binary to Hexadecimal Conversion Lesson 2: Raspberry Pi - Introduction to PythonSuggested time: 50 mins Main:Students were instructed to setup their Raspberry Pis and to launch IDLE 3. Students were then asked to follow Mark Clarckson’s Introduction to Python booklet: (http://community.computingatschool.org.uk/resources/14) Alternative: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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## AuthorSimon Johnson Microsoft Innovative Educator Expert / MIE Trainer
Minecraft Cert. Educator / Global Mentor
CAS Master Teacher
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June 2017
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