There are some lovely ways of Forming Expressions. Students don’t always realise that Algebra isn’t just playing around with letters and that they don’t always have to use formal methods when forming expressions. I like tasks where students really understand how to deal with the letters and are comfortable forming expressions.
Whats nice about the task above is students are able to use numbers first and then apply the same process to letters. I constantly ask students to use a number example to help them. If they are struggling to form an expression for ‘Arun is N years old and if someone is 3 years younger’ for example, you can ask what they’d do if Arun was 10 or 6 or 4 etc. This can quickly be generalised. I don’t ask for the answers in the first two columns but just the calculation you would do.
Another activity I like to use enables students to use their ability to work with number calculations and then by changing one aspect of the problem, they try the same problem again. The first problem raising issues with order of operations and as it deals with money, students tend to find this association easier to deal with. Once they are happy with creating expressions with numbers (the answer isn’t important but students like to calculate them) you can verbally ask them what the expression would be (using the first questions as an example) for 6 days, 7 days, 8 days, n days or £40, £50, £n.
I had a think about how i write expressions. I realise sometimes i use values if i have got mixed up with how to write the expression
I started with some values that students could try and see if they worked, then they could look at the generalised statements; is “Ali always older than Carrie?”
The final one: “Carrie is 11 years older than Ali?” Is it ever true?