Lesson 2 Text ‘n’ talk

# Text and Talk

Text and Talk
Overview Resources
The experience of using a mobile phone is looked at mathematically. Ways of recording the number of text messages sent by a circle of friends are first compared and the two variables identified, then general number and algebra are used to describe their relationship. A different and related situation is then handled, and the generality of algebra is explored in several other real-life situations. Large sheets of paper (A3 or bigger)
Marker pens
Worksheet 1
• Compare ways of systematic generation of outcomes
• Multiplication
• Generalise and use algebra in real-life situations.
• Algebra
• Reasoning and justification
• EPISODE 1
Enumerating text messages

In discussing the features of mobile phones pupils focus on sending text messages. For three people texting each other at the same time they suggest ways of showing on paper the number of text messages, e.g. in lists, using abbreviations, diagrams and so on. They predict the total number of messages for four people, using their method (or another), and attempt to be systematic.

Pupils share their methods and assess the efficacy of different representations. As a whole class they look at a selection of
methods to find the common feature of grouping and the two variables multiplied: number of people and number of text messages per person. They generalise to larger numbers and to ‘any number’ using symbols.
EPISODE 2
Enumerating phone calls

Pupils discuss the number of phone calls needed for two people to have a conversation. They then move to larger numbers and attempt to formulate a rule for the relationship between the number of people and the number of phone calls.

In the sharing phase pupils check and agree the rules generated and discuss the similarity/difference between this rule and the rule for counting text messages. Some will move towards symbolising. They look for other situations of the text messages or the phone calls type, and see how the same formula applies in different contexts.
EPISODE 3
Same expression - different meaning

Pupils handle an expression such as n - 3 in two contexts; they then work to produce their own stories to fit other expressions given in the worksheet. Most of the stories generate linear equations, with a few quadratic expressions as an appropriate challenge for some pupils.