Scientific method

Science aims to develop a good explanation of natural events (phenomena) that are observed.

Scientists use the scientific method to develop explanations. This follows a specific way of working:

  1. propose a hypothesis, which is an initial theory or explanation for an observation
  2. make a prediction based on the hypothesis, suggesting how changing one factor will affect the observation or outcome
  3. plan an experiment to test the prediction and the hypothesis on which it is based

Planning experiments

It is important to choose appropriate apparatus, materials and techniques.

A student using a pooter
A pooter is a safe way to collect insects for study

Apparatus

Containers include:

  • boiling tubes
  • beakers
  • water baths
  • sweep nets
  • pooters

Measuring apparatus include:

Biological apparatus include:

Chemicals for analysis include:

Techniques

Standard techniques of measurement. The table gives some examples.

ApparatusMeasures
ThermometerTemperature
pH meterpH
TimerTime
Digital balanceMass
Measuring cylinderVolume of liquid
BuretteVolume of liquid in titration
Gas syringeVolume of gas

Biological experimental methods include:

  • using a light microscope
  • aseptic technique during microbiological experiments to measure the effect of antibiotics and antiseptics
  • measuring increases or decreases in mass of plant tissue after osmosis
  • testing the efficiency of enzymes at different temperatures or pHs
  • food tests
  • comparing the rate of photosynthesis at different light intensities
  • measuring reaction times
  • determining the effect of light on plant growth
  • measuring the population size of a common species in a habitat
  • comparing the effect of an abiotic factor on the distribution of this species