4 Ask a Question How does fertilizer affect the growth rate of plants? scientists notice something in their natural worldExample: Does fertilizer make plants grow taller?
5 Make Observations Gathered using the 5 senses Record what happens during the experiment in your lab notebookUse black or blue inkThe information you write down is called dataExample: My neighbors’ plants are taller than my plants. He uses fertilizer and I do not.
6 State a Hypothesis A suggested solution to the problem Must be testableSometimes written as If…Then statementPredicts an outcomeExample: If plants are grown using fertilizer, then they will grow taller.
7 Design an Experiment A procedure to test the hypothesis set up an experiment testing different amounts of fertilizer on plants & measuring the growth (height) of the plantsmust contain variables and controlsmay have many controlled factorscan only change one variable
8 Design an Experiment Controls factors that are kept constant not being tested!examples: amount of water, type of soil, amount of sunlight, type of fertilizeract as a standard of comparisonshould not effect the outcome of the experiment
9 Design an Experiment Variables 2 types 1- dependent variable The effect of _____________ on _____________Design an ExperimentINDEPENDENTVariables2 types1- dependent variablewhat you measure in the experimentunpredictable change: we don’t know how it will change until we do the experimentgraph on Y-axisheight of plants2- independent variablemanipulated variablepredictable change: it only changes because we chose how it would changethe more trials… the bettergraph on X-axisamount of fertilizerDEPENDENTThe effect of _____________ on _____________Amount of FertilizerHeight of Plants
10 Collect and Analyze Data May be organized into charts, graphs, tables2 types of dataQuantitativeExpressed mathematically numbersQualitativeDescriptive nature words, feelings
11 How’s a critter to choose? Analyze DataWhat does your data showGraphsline graphsgraphing data that shows continuous changebar graphs (or histograms)graphing data that is in disconnected groups
12 Examples of experiments What’s the favorite drink of students?we set up an experiment surveying students and asking which is their favorite drink :dependent variable (Y-axis)?number of studentsindependent variable (X-axis)?type of drinkThe effect of _____________ on _____________Type of DrinkHow many students chose it
13 Which drink do you like best? numberCoke1PepsiWater4Iced teaGatorade36Bar graph!54number of students32Red Bull?1CokeRBPepsiRBwaterteaGatoradetype of drink
14 elevation (feet above sea level) How does elevation affect temperature?Line graph!elevation (feet above sea level)temp.(°C)30500251000201500152000102500530252018temperature15101200 ft?550010001200150020002500elevation
15 Form ConclusionsAnswer to the hypothesis based on the data obtained during the experimentCheck for biasIn order to verify the results, experiments must beRetestedvalid!Communicate resultsScientists publish work in journals
17 Examples of experiments How does exercise affect heart rate of 10th grade student?we set up an experiment testing different lengths of time of exercise (minutes) on the heart rate of students:dependent variable (Y-axis)?heart rateindependent variable (X-axis)?minutes of exerciseThe effect of _____________ on _____________ExerciseHeart Rate