2 What are the three types Scientific Investigations? DescriptiveInvestigationComparativeExperimentInvolves describing and/or quantifying parts of a natural or man-made systemInvolves collecting data on different organisms, objects or features , or collecting data under different conditions (e.g. times of the year, temperatures, locations) to make a comparison.Involves designing a fair test in which variables are actively manipulated, controlled and measured in an effort to gather evidence to support or not support a causal relationship
3 Basics steps of an experimental investigation 1.Observation2.Hypothesis3.Experiment4.Data Collection5.Conclusion6. Revise/RetestLet’s discuss each step in detail
4 What is an Observation? Gathered through your senses A scientist notices something in their natural world
5 There are 2 types of observations in an experiment? Qualitative:use your sensesto observe the results.OBSERVABLEQuantitative:use tools (rulers, balances, graduated cylinders) to produce numerical data.MEASURABLE
6 Is your observation qualitative or quantitative? Make your observationIs your observation qualitative or quantitative?
7 What is a Hypothesis?a specific, testable prediction about what you expect to happen in your investigationSometimes written as If…Then… statements
8 Checking for Understanding Take out your white boards and markersIs it a Hypothesis?
9 Testable (T) or Untestable (U) Bacterial growth increases as temperature increases.Old people are frail.UTPlants prefer country music to rock musicObjects of different masses dropped from the same height will accelerate toward the earth at the same rateUIf you play music to plants for 8 hours a day they will have increased growthTTMore than 70% of students report that they prefer chemistry to physicsIndividuals that take daily doses of Aspirin for more than 6 months have a 50% increase in reported instances of stomach damageTPhysics is far more interesting than chemistryUTHuman bone density tends to decrease as age increasesPeople that take daily doses ofaspirin feel better.TU
10 What is an Experiment? A set of actions to test a hypothesis Uses variables – factors in an experiment that changeA valid (correct) controlled experiment will only test ONE variable at a time
11 What are the two important GROUPS in an Experiment? Control Groupused for COMPARISONNOT being tested (what is normally done)Experimental Groupthe subjects being TESTED
12 Within the Experimental Group are variables Independent Variable (IV):Factor that is purposely MANIPULATED (CHANGED) in the experimentDependent Variable (DV):Factor that RESPONDS as a result of the IV (it’s observed or measured)
13 CONSTANTSthose conditions in an experiment that are kept the same for the experimental group.
14 Experiment investigation Scenario Ten seeds were planted in each of five pots containing 700g of “ Sure Potting Soil”. Each day for 40 days, spring water is given weekly as follows:Pot #1, 50 ml;Pot #2, 100 ml;Pot #3, 150 ml;Pot #4, 200 ml;Pot #5, 250 mlThe recommended amount of water use is 150 ml. The student decided to measure the height of each plant at the end of the experiment.Identify the Following:A. Control Group:- Pot #3B. Experimental Group:- seeds in Pot#1,2,4,51. Independent Variable:- Amount of water2. Dependent Variable:- height of each plant3. Constants:- duration, “sure potting soil” , 700g of soil, spring water
15 What is Data?information gathered during the experiment (quantitatively or qualitatively)it can be represented in the form of notes, charts, graphs, pictures etc.
16 What is the Conclusion?The answer to the hypothesis based on the data obtained from the experiment
17 Why Retest?In order to verify the results, the experiment must be retestedThe more trials performed the more accurate the results.
18 Can you state the steps involved in solving a problem? 1)Identify a Problem2) State Observations about the problem3) Form a Hypothesis about the problem (if…then…)4) Design an Experiment to test the hypothesis5) Collect Data6) Form a Conclusion7) Retest
19 What is a Scientific Theory? An explanation of an observation that has been confirmed through repeated testingIt unites and explains a broad range of observationsIt remains valid as long as there is no evidence to dispute itIt is not easily disproven – BUT CAN BE!
20 So then, What is the difference between a hypothesis and a theory? A hypothesis attempts to answer questions by putting forth a prediction or reasonable explanation that has not been thoroughly tested.A theory, on the other hand, has already undergone extensive testing by various scientists and is generally accepted as being an accurate explanation of an observation.(This doesn’t mean the theory is correct; only that current testing has not yet been able to disprove it, and the evidence as it is understood, appears to support it.)