Vicky Hall

Vicky Hall commented on Find and use the formula for a geometric sequence 7 years, 9 months ago

I have added a sentence to the statement to explain what is meant by the common ratio. I think part a) should include one sequence with a positive integer ratio, one with a negative integer ratio and one with a fractional ratio to cover all possibilities.

Vicky Hall on Finding the formula for the $n^{\text{th}}$ term of linear sequences 7 years, 9 months ago

Gave some feedback: Has some problems

Vicky Hall commented on Finding the formula for the $n^{\text{th}}$ term of linear sequences 7 years, 9 months ago

Change the question to 'find the formula for the $n$th term'. It would be good to have one increasing and one decrasing sequence to show that sometimes the $n$ coefficient is negative.

Vicky Hall on Finding the $n^{\text{th}}$ Term of a Quadratic Sequence 7 years, 9 months ago

Gave some feedback: Has some problems

Vicky Hall commented on Finding the $n^{\text{th}}$ Term of a Quadratic Sequence 7 years, 9 months ago

I would reword the question to say 'Find the formula for the $n$th term of the quadratic sequence'.

The advice is good but think the last part, where you find the constant, would look better if it were laid out like the previous part, so you show the student what the sequence $3n^2+3n$ looks like compared to the original sequence. You also need to remove the reference to part b).

Vicky Hall on Factorising Quadratic Equations with $x^2$ Coefficients Greater than 1 7 years, 9 months ago

Gave some feedback: Has some problems

Vicky Hall commented on Factorising Quadratic Equations with $x^2$ Coefficients Greater than 1 7 years, 9 months ago

The statement is exactly the same as the other quadratic equations questions, but this time its not true that $ax^2+bx+c$ factorises to $(x+m)(x+n)$ - the $x$s need coefficients.

I think there should be two more parts to this question, a question at the beginning that only wants to students to factorise, and a question at the end that doesn't give them one of the $x$ coefficients.

It would also be very helpful to tell students in the statement that we can sometimes divide through by the $x^2$ coefficient to obtain a simpler equation, but sometimes the coefficent is not a factor of all terms so we can't. (I know you show this in the advice but it would be nice for the student to see this before they try the question as otherwise they will start looking for factors of the existing numbers). 

Vicky Hall on Cumulative percent decrease 7 years, 9 months ago

Gave some feedback: Has some problems

Vicky Hall commented on Cumulative percent decrease 7 years, 9 months ago

Make sure all number are in Latex. I think the statement needs changing 

Check your tenses. For example, 'How much is it worth after 5 months?' would read much better as 'How much will it be worth after 5 months?'. Also, 'After how many more months is the smartphone's value going to be £511.19?' would be better as 'After how many more months will the smartphone's value be £511.19?'.

In part c), I would say leave out the word 'exponentially' and change the next sentence to say 'What was the average percentage increase per year?'.

Vicky Hall commented on Factorising Quadratic Equations with $x^2$ Coefficients of 1 7 years, 9 months ago

I think this question should be renamed to 'factorising quadratic equations with $x^2$ coefficient $1$, and your other question (Factoring quadratics with larger coefficients) should be renamed 'factorising quadratic equations with $x^2$ coefficient greater than $1$.

There should be another line in the statement that shows how to solve the equation if it factorises to $(x+m)(x+n)=0$, as you ask the student to solve in the final part of the question. 

In part a), I think it's a good idea to have a difference of two squares example to get students to think about how the equation can sometimes look a bit different. However, I think this should be moved to a subpart iii), and subpart i) should have a straightforward quadratic that looks exactly like the general form $ax^2+bx+c$.