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. 

Change/Control	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?
Organism	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.
Repetition/Replication	You MUST take more than one reading- you should take a minimum of 3 readings and repeat the whole experiment.
Measurement	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.
Same/Standard	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.