Level Control Level Level Level Number of trials Number of trials Number of trials - PDF document

OWCANWENDERSTANDOURATER ESIGNINGANhe information in this chapter is ashort summary of some topics that arecovered in depth in the book and Researchwritten by Cothron, Giese, andinformation on obtaining this book. The bookis an invaluable resource for any middle orhigh school science teacher.ARTSOFANThere are different types of practical activitiesthese would strictly be considered experiments.When younger students begin learning how tois often referred to as a “fair test.” The experi-ment can be a test of the effect of differenttest comparing differing conditions as somemight test the effect of different wateringschedules on plant growth. Or students might try removing a stain using different stain removers to find out which one is considered experiments. For example, carryingout an exercise to measure the density of adifferent types of plants and animals foundalong a stretch of beach. be identified by students. These different parts can all be checked off during the designconsidered carefully before the experiment isstarted it is more likely to be a successful andThese are the response to the purposeful change; this is therespondingvariableshape of a paper airplane and measure theresulting time that the plane stays in is most interested in to change. There will normally be many other factors that couldchange and have an effect upon the outcome be controlled or held constant. Any effect on OWCANWENDERSTANDOURATERconclusion can therefore be reached about the effect of this factor. The factors that couldbe changed but which are deliberately heldconstant are referred to as experiment. Constants are sometimes referredto as controlled variables, but this term can beby the experimenter will have several differentvalues, and these different values are calledexample, if temperature were the independent30ºC, and 40ºC might be the different levels.variable is the reference point or “normal”will be compared with this one in order todraw conclusions from the experiment. Thisreference level of the independent variable,which other levels will be compared to, iscontrolexample given here, 20ºC would likely be thecontrol because this represents normal roomtemperature.Another part of the experiment related to therepeatedvariable. If the experiment is repeated morevariable this will make for a more reliable test.The possibility of obtaining a misleading resultdue to experimental errors will be less. Everyand then the results of the individual trialsaveraged together. When it comes to countingthe number of repeated trials that are carriedber of measurements that are made. For exam-ple, if a flat of 12 plants is grown using a par-ticular kind of fertilizer, and the height of eachindividual plant is recorded, then the numberof repeated trials is 12. The recommendednumber of repeated trials that should be usedwill vary depending on the exact nature of the experiment. However, as a general rule,students should repeat the experiment asLastly, students should be asked to formulateor “educated guess” before theya predicted outcome for the experiment, and itas well as information they have been able togather while carrying out background researchwritten in the form of an “if-then” statementa predicted change in the dependent variable.paper airplane is increased, then the directionof flight will be more of a straight line.”XPERIMENTALalways do this before they begin an experimentto make sure that they have remembered eachpart. The “diagram” is not really a diagram, ESIGNINGAN OWCANWENDERSTANDOURATERbut more of a visual layout ofThere are eight essential parts to design diagram, reflecting theare listed below and then laidout in the “diagram” format.1.Title for experiment written as“the effect of the independent2.Hypothesis in the form of an 3.Independent variable4.Different levels of the 5.Level of the independent control for the experiment6.Number of repeated trials for7.Dependent variables, includinghow they will be measured8.Constants ESIGNINGANThe Effect of _______________________________________ (Independent Variable)on _________________________________________________ (Dependent Variables)then ____________________________ (predicted change in dependent variables).EVELSOFARIABLEANDUMBERSOFEPEATED)Level 2Level 3Level 4Number of trialsNumber of trialsNumber of trialsNumber of trialsARIABLEANDONSTANTS The Effect of Type of Insulation Wrap on Temperature of Water in a JarType of insulationEVELSOFARIABLEANDUMBERSOFEPEATEDCottonWoolNylon3 jars3 jars3 jars3 jarsARIABLEANDChange in temperature of water in jar, measured in degrees CelsiusONSTANTS OWCANWENDERSTANDOURATERTRATEGYIt is always extremely difficultinterest, but it is still not easyto translate this general area of interest into a focused topicfor study. The four-questionto help students explore thetopic before attempting to statec problem, hypothesis,trol. When we teach studentsthe process of experimentalpractice this four-questionbefore asking them to designstudents in a class throughone example of the four-question strategy, alltogether, using the chalkboard. The studentscan then practice the four-question strategy,alone or in small groups, using a prompt pro-vided by the teacher, before attempting to workthrough the four questions for an experimentthat they areinterested in carrying out. ESIGNINGAN The four-question strategy involves the followingQuestion 1 – What materials are readily general topic of interest)Question 2 – What action is observed whenstudying (general topic of interest) OWCANWENDERSTANDOURATER ESIGNINGANQuestion 3 – What are all the ways that IQuestion 4 — In what ways can I measure ordescribe the response to the changeA specific experiment follows from the answersto the four-question strategy. One of thebe changed to make an effect, will need to becontrolled when the experiment is carried out.The following example of the four-questionbe answered using the general topic of plants.What materials are readily available for con-Soil, Plants, Fertilizer, Water, Light/Heat,How do plants act?Plants growHow can I change the set of plant materialsto affect the action?Water: Amount, Scheduling, Method of appli-cation, Source, Composition, pH(Possible changes in Soil, Fertilizer, andHow can I measure or describe the responseMeasure the length of the longest stemDetermine the rate of growthWeigh the fruit producedMeasure the diameter of the stemOnce students have carried out the four-create an experimental design diagram for anbe ready to proceed with writing an experimen-tal procedure to follow for their experiment.design process by providing a prompt to helpthe students begin the four-question strategyactivity. You can provide the students any ofbegin the four-question strategy.Lists of simple and available materialsQuestions to be investigatedNews briefs or articles that lend themselves OWCANWENDERSTANDOURATER ESIGNINGANScience demonstrations in a bookTextbook or laboratory activitiesLibrary bookWhatever type of prompt is used, it should be chosen so as to stimulate student interestStudents and research: Practical strategies for science classrooms and competitions.Cothron, J. H., Giese, R. N., & Rezba, R. J.(3rd Ed.). (2000). Dubuque, IA:This book provides all the information youwill need to know about teaching K – 12