Home > IB Computer Science 2015, IB Computer Science 2016 > what, when, how, why, otherwise

what, when, how, why, otherwise

February 2, 2015 Leave a comment Go to comments

One of the commonest sources of lost marks in tests is that students fail to state the obvious. They rock back in their chair and then write down their stream of consciousness.

I recommend you keep this mnemonic in mind:

What When How Why Otherwise

Sample question:

Outline how encryption should be used in an online banking website? [4 marks]

Bad answer:

It is very important that encryption should be used in an online banking website for a large number of reasons. Firstly, it should used to keep customers’ information safe. When they type their password it has to be hidden so that attackers cannot get it. Also encryption should be used to check that customers are who they say they are. Finally, encryption can be used to prevent viruses.

Why is this bad?

It is very important that encryption should be used in an online banking website for a large number of reasons.
This is introductory waffle that CANNOT EVER SCORE MARKS. You have all done it. Stop it.

Firstly, it should used to keep customers’ information safe.
Great… and… what information? Don’t hint at the answer. State the obvious.

When they type their password it has to be hidden so that attackers cannot get it.
Sure, but how does this happen? And what would the consequences be if it didn’t?

Also encryption should be used to check that customers are who they say they are. Finally, encryption can be used to prevent viruses.
Both factually incorrect. This student has run out of ideas and has is now saying stuff that is just plain wrong.

Score: 1/4 for mentioning passwords

Good answer:

First we structure our answer using what when how why otherwise:

  • What: Sensitive information like passwords or credit card details.
  • When: Before it is sent out over a network.
  • How: Using one of a variety of standard algorithms, e.g. RSA, which allows the user and the bank to be able to encrypt and decrypt information for each other.
  • Why: So that if it is intercepted the information cannot be read.
  • Otherwise: Malicious network users would be able to impersonate you online and may be able to steal money from your bank account.

And then we write a sentence for each:

Sensitive information like passwords or credit card details should always be encrypted before being sent out across a network. Encryption can be done in a variety of ways using standard algorithms such as RSA, which allows the user and the bank to encrypt and decrypt data that they are sending to each other. Encryption is important to prevent unauthorised people from being able to read information if they intercept it. Without encryption, malicious network users would be able to intercept and read customers’ information, including passwords, allowing them to impersonate the customers and steal their money.

Score: 4/4

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