Scientific investigation

What is the scientific method?

Observe

Question

Hypothesis

Experiment

Conclusion

Lab 2

scientific-method

Scientific Questions:

  • Must be objective and testable
  • Must focus on defined independent & dependent variable
  • Elements must be measurable and controllable

Examples

Does changing the temperature of water affect the buoyancy of an egg?

What is the effect of pH on the lifespan of tadpoles?

Do fertilizers affect the health of earthworms?

Does the direction seeds are planted affect plant growth?

What is the effect of increased or decreased oxygen on plant growth?

Hypothesis

  • Is a proposed explanation
  • Must be testable and falsifiable
  • Can be summarised as assumption based on evidence

Example

Will increased levels of O2 stimulate plant growth?

  • Increase levels of O2 increase plant growth
  • Increased levels of CO2 decrease plant growth

How is hypothesis tested?

Controlled experiment

Accumulate data

Interpret results

Designing controlled experiment

  • Define variables
  • Outline procedure
  • Establish controls

Variable types

Independent variable = choose one variable or condition to change

Dependent variable = measured in response to independent variable

Controlled variables = factors other than independent that can be controlled

Outlining procedure

  • Number of steps
  • Recorded beforehand
  • Include value set of independent variable
  • Mention how many repeats
  • Include any controls for benchmark

Making predictions

Predictions are often written in the form of “if, and, then” statements, as in, “if my hypothesis is true, and I were to do this test, then this is what I will observe.”

Examples

If you keep the curtains closed, then you need less electricity to heat or cool the house

If you leave a bucket of water uncovered, then it evaporates more quickly.

If you leave the lights on, then it takes longer for people to fall asleep.

Presenting & Analysing results

  • Data must be summarised in tables and figures
  • Helps analyse and interpret results
  • Enhance clarity

Tables

  • Same kind of values form a column
  • Remove unessential information
  • Include units on headings
  • Title on top

Figures

  • Such as graphs, diagrams, drawings etc
  • Use graph paper and ruler
  • Include x and y axis
  • include units on labeled axis
  • Choose appropriate scale
  • Title below figure
  • consecutive numbering

cool

graph

nice

scientit

click to edit