Transition to university

Elliott Fletcher commented on Calculate density given mass and volume 8 years, 4 months ago

I have begun rewriting the step in order to add the mass/density/volume pyramid, but a custom made pyramid will have to be made in inkscape for this question.

Elliott Fletcher on Cumulative percent decrease 8 years, 4 months ago

Saved a checkpoint:

I have rewritten the step so that it includes the variables in the question and gaps asking the student to calculate the decimal multiplier for the decrease and the value after the first month and then after another month.

I have also added a precision hint for the answer in part a).

Elliott Fletcher on Cumulative percent decrease 8 years, 4 months ago

Gave some feedback: Needs to be tested

Chris Graham on Find the equation of a line through two points - negative gradient 8 years, 4 months ago

Gave some feedback: Ready to use

Chris Graham commented on Find the equation of a line through two points - negative gradient 8 years, 4 months ago

I've changed some of the simplification rules in the advice, corrected the calculation for the gradient and other inconsistencies with regards to the order of points A and B. Fixed some typos.

Elliott Fletcher on Geometric Sequence - negative ratio 8 years, 4 months ago

Gave some feedback: Needs to be tested

Chris Graham commented on Find the equation of a line through two points - positive gradient 8 years, 4 months ago

The points A and B should be switched; it doesn't make sense to describe the leftmost point as B, and in fact the gradient is calculated from A to B in the advice. There are places in the advice where $y_1-y_2$ needs to be inverted.

Chris Graham on Find the equation of a line through two points - positive gradient 8 years, 4 months ago

Gave some feedback: Has some problems

Chris Graham on Use speed and distance to calculate time 8 years, 4 months ago

Gave some feedback: Has some problems

Chris Graham commented on Use speed and distance to calculate time 8 years, 4 months ago

Context is good, and the variables are realistic.

"We can rearrange the formula for average speed to give us the formula for the time taken" - again I would give the speed/distance/time pyramid here, and then pick out the relevant equation.

Chris Graham on Calculate density given mass and volume 8 years, 4 months ago

Gave some feedback: Has some problems

Chris Graham commented on Calculate density given mass and volume 8 years, 4 months ago

At this level, I think it would be appropriate to add the classic mass/density/volume pyramid as an image in the step and all 3 equations, then let the student pick out the equation that they need to use. 

The advice is a little wordy: it takes the first 3 paragraphs and equation to explain that 1kg is 1000g. 

The question desperately needs a bit of context to make it interesting. There are many, many possibiities. See e.g. these Geoscience examples: https://serc.carleton.edu/mathyouneed/density/densitysp.html

Chris Graham on Geometric Sequence - negative ratio 8 years, 4 months ago

Gave some feedback: Has some problems

Chris Graham commented on Geometric Sequence - negative ratio 8 years, 4 months ago

Lots of problems with this:

In the question,

• The answer for (b) appears to use the wrong value for a.
• The prompt in (c) asks a term, but then has "common ratio = ..." before the gap.

In the advice,

• I would prefer the table cells to contain the calculation for the common ratio, rather than below, and express as a fraction, e.g. $\frac{-12}{36}=-3$.
• The values for $a_n$ appear to be wrong in the table.
• "Common ratio as..." then seems to give the wrong common ratio (wrong sign at least).