Presentation on theme: "Processes of Science. Designing an Experiment Typically begins with observations that lead to a question Tests a hypothesis (prediction) Collect information."— Presentation transcript:
Designing an Experiment Typically begins with observations that lead to a question Tests a hypothesis (prediction) Collect information under controlled conditions. Control group – all conditions kept normal Experimental group (test group) – all conditions kept the same as the control except for the single condition being tested
Variables Independent variable – condition that is changed: affects the outcome (a.k.a. the manipulated variable) Dependent Variable – changes in this condition depend on changes in the independent variable (a.k.a. the responding variable)
Variables Ex. You want to test the effect of calcium additives on the growth of tomato plants. What is the independent variable? What is the dependent variable? Your control group would be put in what conditions? Amount of calcium Growth of tomato plants Normal soil without calcium added
Data Quantitative – numerical counts or measurements Scientific measurements are always metric! Reported in graphs or tables Qualitative (descriptive) – written descriptions When would you use each of these? Data often presented in tables or graphs.
Conclusions Data lends support for or against the hypothesis When a hypothesis is supported over time by many investigations is becomes a theory A theory is an explanation of a scientific event. Ex. Theory of Inheritance Facts of nature generally known to be true are laws Ex. Law of Gravity
What is the difference between a theory & a law? A theory is an explanation of why something happens A law simply describes a natural phenomenon (does not explain why). Theories & laws are accepted to be equally legitimate.
Peer review Results from experiments are reported to the scientific community. Why is this important? The researcher may then repeat the experiment to verify results, or redesign the experiment as needed.