Variables

NAME: _____________________________________ DATE: ______________

Classwork No 2: VARIABLES An important criterion of assessment for the checkpoint is to be able to identify DEPENDENT, INDEPENDENTand CONTROL variables in an investigation. DEPENDENT and INDEPENDENT variables CHANGE during an experiment. CONTROL variables SHOULD NOT CHANGE (or only by very small amounts not likely to affect theexperimental results.) The problem is then how to distinguish between the INDEPENDENT and DEPENDENT variables. The INDEPENDENT variable is the one that the experimenter is free to change during theexperiment. On graphs, it should always appear on the x-axis. The DEPENDENT variable is the one she / he must observe changing and measure (y-axis) For instance, in the research question: “What is theeffect of different drinks on the time we sleep?” INDEPENDENT = type of drink DEPENDENT = sleep time CONTROL variables = volume of drink, time drunk, state of tiredness etc. Activity Study thefollowing research questions and try to decide which variable is independent, dependent and think of 3 control variables (it is not common to have more than one dependent variable and one independentvariable) Underline with red the independent variables and with blue the dependent variables: 1. How does the colour/shade of a flower change with exposure time to sunlight? 2. How is the time taken for foodto go bad affected by cooking salt concentration? 3. How does concrete setting time vary with temperature? 4. Is there a difference in the amount of heat evolved by different types of “super-glue”? 5.Is there a connection between the melting point of plastics(type) and how much they will bend? 6. How does wing area affect the flight time of a paper plane? 7. Is there a connection between pageedge colour and the age of books? 8. Is there a relation between how fast a person moves through the rain and how wet they get? 9. How does temperature vary with height at different points on the...