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<mdoxml version="1.0"><p>Here is the alphabet:</p>
<p style="font-family: Comic Sans MS; text-align: center;">a b c d e f g h i j k l m n o p q r s t u v w x y z</p>
<div> </div>
<div>What happens if we change the rule for decoding so that we move the letters $3$ places to the right?</div>
<div style="text-align: center;"> </div>
<div>Try to decode these messages using this new rule,</div>
<p style="font-family: Comic Sans MS; text-align: center;">cfka - x - ylxq,</p>
<p style="font-family: Comic Sans MS; text-align: center;">fqp - qfjb - ql - mixv</p>
<p style="font-family: Comic Sans MS;"> </p>
<p>Can you invent some messages of your own?</p>
<p>Can you create some different ways of coding?</p>
<p> </p></mdoxml>
<mdoxml version="1.0"><br></br>
<h3><span style="font-weight: bold;">Why do this problem?</span></h3>
<div>This <a href="http://www.nrich.maths.org/7992">activity</a> enables pupils to use some simple counting in addition and subtraction situations. It also starts pupils thinking about codes and the fun that can be had with them.</div>
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<h3>Possible approach</h3>
<div>The activity can be started off as a game in which the teacher says something about some secret ideas/thoughts they are having when looking at the alphabet. So, with the alphabet displayed as separate cards in order in front of the pupils they say they want to spell out (eg dog) but carefully goes for g r j instead of d o g.This will obviously lead to some discussiion. Perhaps other examples
will be needed until the "rule" is extablished.</div>
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<h3>Key questions</h3>
<div>What do you think has happened?</div>
<div>What letters will you choose?</div>
<div>I see you've made your own code, can you tell me about it?</div>
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<h3>Possible extension</h3>
<div>Go along to "<a href="http://nrich.maths.org/7624">Secret Codes</a>" .</div>
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<h3>Possible support</h3>
<div>Some children will need the alphabet individually in front of them.</div>
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<br></br></mdoxml>
<mdoxml version="1.0"><p>You could try writing the letters round in a circle so that it is easier to count forwards and backwards.</p></mdoxml>
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Some Secret Codes part 2
Can you follow the rule to decode the messages?
Calculations and Numerical Methods
Addition & subtraction