Skills

What we are assessing in DCP is whether students can organise raw data into tables, process the data with a spreadsheet and produce a graph from the processed data complete with error bars and best fit lines. So we are looking at organisational as well as mathematical skills, a student who is not well organised will get lost in all of the numbers. I say processed with a spreadsheet because this is what I do with my students, according to the IB requirements you actually only have to do this once but if you are going to teach your students how to do this once then they might as well do it all the time. I start the course with some exercises to introduce the students to the use of Excel and the graph plotting programme LoggerPro from vernier, once students see how to fill a column with a formula by simply dragging the corner they don't go back to paper and calculator. It's funny though; my students all have computers on the table whilst doing lab work but still scribble the results onto scraps of paper (and so do I).

The area that provokes the most discussion isn't the processing of data but the estimation and processing of the uncertainties. Our aim is that students gain an appreciation of uncertainties in experimental data and the need to process them through calculations. The skill that we want the students to acquire is the skill of being able to estimate (if that is a skill), once they have estimated the uncertainty the rest is maths. To clarify the way that  I do this see the separate section on uncertainties.

Criteria

Exercises

When we say "processing" we mean doing some mathematical manipulation to the data like squaring finding the reciprocal or at very least finding the average, simply plotting V against I isn't enough. I like to make it clear that the students have done something so prefer to use examples where they have had to perform some calculation but finding the average is technically enough. When students design their own experiments they often simply plot the one variable against the other, this means you can't award the top score for these examples. I don't want to prevent students from being creative in the Design stage so offer a large number of straightforward practicals where some processing is necessary. You can find all of these in the DCP and CE practicals section. Beware though, although you can make it straightforward you can't tell the students what to do; giving them the equation fλ=(T/μ)½ is ok but you can't tell them to plot a graph of wavelength against the square root of tension, they have to work that out for themselves.