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Sunday, 6 May 2012

Planning an experiment

So I was taught to use CORMS. Basically  when you plan an experiment, do it logically and make sure what you're measuring is relevant to your investigation. 

Have some repetition in it so that you can have comparison, and to reduce risk of errors and anomalies. If you were to only take one measurement, and it's wrong, you would not have any valid data. 

What factor are you investigating? Will you have a range of values? (You should always have a minimum of 5 values in a range) Or will you have two groups, one with the factor and one without? What is your control?
What species/size/age/gender will you use? Note if you were planning an investigation into enzyme activity, you would identify the enzyme and the substrate.
You MUST take more than one reading- you should take a minimum of 3 readings and repeat the whole experiment.
What will you be measuring, how often and what are the units? You should describe how you will take the measurement, and with what equipment.
You must say what factors you will keep the same to make sure you have carried out a fair test, e.g. temperature/light intensity/volume of water etc.

Effect drinking tea has on heart rate

Change- 2 groups: one group with tea, the other with water

Organism- human, same gender + same age

Repetition- how many people in each group

Measurement- heart rate in beats per minute, describe how you would do this, and when

Same- temperature of tea/water, volume of tea/water, level of exercise before drinking tea, same room/temperature of room

After considering these factors you should then write your description in full.


  1. whaatt...I have not learnt this...I clearly don't have very good teachers! Thanks Michelle, this is literally so helpful! :)

    1. Literally, really?

    2. was kind of helpful. thanks

  2. Thanks Michelle, this is metaphorically so helpful !!!

  3. Thank you, that was very helpful!!

  4. When we learnt this, we were told to look at what we were measuring and how we would measure it. For example, the heart rate can be measured by checking their pulse after 5 mins, 10 mins, etc.

  5. Thanks, very helpful! This is pretty much in every IGCSE exam.

  6. That's extremely helpful for me. Thanks for sharing the details here.

  7. Thanks this is my exact homework question! It is in literally every IGCSE test I have done.

  8. Awesome-keep up the solid work! YES!

  9. This was really helpful, thanks!

  10. you are absolutely right

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  12. Why is C for Change and Control? Control variables always stay the same so shouldn't C just stand for change since it's talking about range or difference?

    Other than that, very helpful- thanks!

  13. this was very useful thanksssssssssss


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Note: This blog will no longer be updated as I finished IGCSEs in 2012. Sorry! :( If you are interested in buying IB notes though, please contact me. :)