Teaching experimental design
- 1. Teaching experimental design Year 7 Integrated Curriculum
- 2. What is an “experiment”? • In school, “experiment” is often used to describe hands-on experiences
- 3. What actually is an “experiment”? • A science experiment tests a hypothesis
- 4. Components of an experiment • Background research • Aim • Hypothesis • Equipment • Types of variables • Results • Discussion • Conclusion
- 5. Background research • Every experiment starts with a topic of interest (Eg. What are the effects of ocean acidification on living things?) • Background research finds out what we already know about the topic
- 6. Aim • Always starts with “To” • Tells the reader what the experiment aims to do • Eg. To find out how ocean acidification affects the shells of living things
- 7. Hypothesis • A prediction of the results based on the background research • Example – The more acidic the ocean is, the quicker the shells of ocean invertebrates will dissolve If A happens then B will happen
- 8. Equipment and Method • List the equipment used in the experiment • Method lists how to do the experiment in steps • Always starts with a verb • Accompanied by a scientific diagram where appropriate
- 9. Types of variables • Independent variable – What we change on purpose (Eg. how acidic the water is) • Dependent variable – What we measure as the result (Eg. How much shells have dissolved after 3 days) • Controlled variables – What we keep the same to keep the experiment fair (Eg. The amount of acids and water; the type of shell; the temperature of the environment) • In most experiments there is ONE independent variable, ONE dependent variable and many controlled variables
- 10. Types of variables - Strategies • Cows Moo Softly – Change one thing – Measure one thing – Keep everything else the same
- 11. Controlled variables vs control 3M HCl with 2M HCl with 1M HCl with Water with shell shell shell shell •Independent variable - concentration of acid •Dependent variable – how much each shell dissolves •Controlled variables – time of experiment, amount of acid and water, type of shell •Control – the water with shell
- 12. Validity and reliability • Validity – Is the experiment testing what you intend to test? • Reliability – Are these results a fluke? If I repeated the experiment again, will I get the same results?
- 13. Replication • You shouldn’t just have one beaker of 3M acid, one beaker of 2M acid, etc. • You need 5 beakers of each acid so that there is replication. • Replication increases reliability. • You’ll need to use average calculations.
- 14. Results • A table and graph must be done • A graph shows patterns that cannot be seen easily in a table • It’s usually a choice between a column graph or a line graph • X-axis = independent variable • Y-axis = dependent variable
- 15. Discussion – analysis of results • What do the results mean? • Are the results expected? Are there any usual results? • What were some possible sources error? • How can the experiment be improved? • What are some other experiments to do in the future?
- 16. Conclusion • The aim written in past tense and says whether the hypothesis is correct • Eg. The effects of ocean acidification on shells were determined. The more acidic the water, the faster shells dissolve. The hypothesis was correct.