Common flowchart symbols: Unplugged algorithm activities

A flowchart is a diagram which represents a set of instructions, it shows the step by step solution to the problem. They normally use standard symbols to represent different types of instructions. Our dear Sheldon, for those who are Big Bang enthusiasts, will recall Sheldon’s  Friendship Algorithm below.

So what are the common symbols?

  • “Start and end symbols, represented as lozenges, ovals or rounded rectangles, usually containing the word “Start” or “End”, or another phrase signalling the start or end of a process, such as “submit enquiry” or “receive product”.
  • Arrows, showing what’s called “flow of control” in computer science. An arrow coming from one symbol and ending at another symbol signifies flow passes to the symbol the arrow points to.
  • Processing steps, represented as rectangles. Examples: “Add 1 to X”; “replace identified part”; “save changes” or similar.
  • Input/Output, represented as a parallelogram. Examples: Get X from the user; display X.
  • Conditional (or decision), represented as a diamond (rhombus). These typically contain a Yes/No question or True/False test. This symbol is unique in that it has two arrows coming out of it, usually from the bottom point and right point, one corresponding to Yes or True, and one corresponding to No or False. The arrows should always be labelled. More than two arrows can be used, but this is normally a clear indicator that a complex decision is being taken, in which case it may need to be broken-down further, or replaced with the “pre-defined process” symbol” (source).

BBC Bitesize offers a good explanation for primary students and offers an online test for students. Students can draw flowcharts or use Microsoft Word (insert shapes function) to create flowcharts.

So what might you ask students to create flow charts on? The possibilities are endless. It really depends on the age of your students and how you can integrate this with other subjects. Keep in mind, with such a full curriculum and often limited time allocated to technology subjects, it is essential to link different subject areas where possible. I’ve provided you with some suggestions below, if you’d like to add some of your own thoughts, leave a comment at the bottom of this blog post.

  • Should I worry?
  • Should I play Mine-craft before bed?
  • Should you friend your parents on Facebook?
  • Should I eat healthy food?
  • Should I do my homework now?
  • Should I listen to my mother?
  • Should I play X Box all the time?

Nrich.maths.org offers a great activity where students choose starting value and then try and establish what the flow chart does. This is a higher order thinking task for secondary students.

 

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