Common problems on lab reports

After reading over the lab reports, there were several common problems.  Here is an overview.

  • Hypothesis. What exactly is a hypothesis?  There is an actual thing called a hypothesis and there is hypothesis testing.  However, just about every student that used this word used it incorrectly.  My suggestion is to just not use this word.  Instead, focus on model building.
  • “I learned a lot”. Remember, the report is about building a model. Hopefully you learned something, but it’s not really relevant in the report. I am only commenting on this because it was a very common statement in the reports.  Not sure why so many people stated this.
  • Human error. Please don’t use this term or any term similar to it. If there was a problem that human caused – just explain that problem. If it was a calculation error – how do you know it was a calculation error?  If the measurements were poor – just describe in what way the measurements were inaccurate.  Saying human error just glosses over the problem.  Repeat – never use this in your lab report.
  • “I proved that …”  Science doesn’t prove anything to be true.  If you drop a ball 1000 times and it falls, do you prove that balls fall?  No, because what if you drop it the 1001th time and it doesn’t fall.  You have shown that it is very likely to fall (or you have built a falling ball model) – but you didn’t prove anything.  On the other hand, you can prove things to be false.  If I say the acceleration is constant and just find one case where the acceleration changes, it’s ok to say you proved constant acceleration is incorrect.

Bonus video

  • Gather materials. I understand why this is in the lab report – but if you want to leave it out, that would be fine with me.  In general, I encourage students to write a lab report so that other students in the same lab could reproduce your results.  You can make assumptions that they have access to the same stuff you have access to.
  • Scatter plot instead of bar graph or line graph. There is rarely a reason to include a bar graph or a line graph.  You probably want a scatter plot.  If you don’t know the difference between these graph types – just make a graph on graph paper.
  • Graphs with linear fits and slope. Just about every time you make a graph, it should be to show a functional relationship between two things.  If this is a linear relationship, you can fit a linear function to the data (a best fit line).  Why include a best fit line if you don’t also include the slope of that line.  Might as well also put this slope on the actual graph.  In your analysis be sure to explain what that slope means (and the units for the slope).
  • Paraphrasing other students or other materials.  I made this clear in class, but if you are just paraphrasing something – that is copying.  Don’t copy.  Write your own words.
  • Misspelled words. Why?  Why are there spelling errors in your lab report?  I assume you are using some type of word processor.  Don’t these programs tell you when something is spelled incorrectly?
  • Self Edit. Don’t write something and then just move on.  This lab report is going to be turned in for an actual grade in a real class.  Take the time to go back over what you wrote – or have a peer or tutor also look over your lab.  It might help to write something and then take another look at it the next day.  Looking at student reports, it’s very clear that some of you just wrote stuff without reading it.
  • “Overall, this was a fun lab”.  I’m glad you had fun – but what about your physics model?  Again, just focus on the model.  Now – this doesn’t mean that you have to be all stuffy and formal.  Feel free to write in any style that you like – but in the end it’s your model and the analysis of your model that really matters.

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