1.5 The Scientific Method

Refer to page 12 of your notes The Scientific Method is used by researchers to support or disprove a theory. It can be used to answer True-False questions only. For example: Not Valid : Why do giraffes have long necks? At first glance, this question seems quite scientific. However, questions of this type cannot be proven scientifically. The best you can do is come up with a believable theory, such as "Assuming Darwin's theory of evolution, giraffes with long necks have evolutionarily had an advantage over giraffes with shorter necks."

Refer to page 12 of your notes 1 Observation Use our five senses (sight,smell,hearing,taste & touch) and other equipment to make observations and gather information 2 Question Ask a question about what your observe 3 Hypothesis Analyse - Study the information closely Predict - Propose a hypothesis to predict 4 Method Plan Experiments to test your hypothesis Decide (1) the purpose/hypothesis (2) what apparatus to use (3) what procedures to take to ensure a fair test to prove the hypothesis The outcome must be measurable (quantifiable) 5 Results Record your results in a table form Plot the experimental data to analyse/interprete the results (E.g: Bar Chart,. It provides a clear visual description of the data) If they do not support the hypothesis, (1) repeat the experiment or (2) change the hypothesis and experimental procedures 6 Conclusion You state whether your hypothesis was confirmed or not and try to explain your results. A conclusion will often lead to another question, which can lead to another experiment, which can lead to another conclusion, and on and on.

Refer to page 12 of your notes Science is like doing a giant puzzle, with the handicap that you are missing an unknown number of pieces. Questions Experiment Conclusion

Refer to page 12 of your notes Detective Skills Observation Some of the skills that scientists use are the same as those used by detectives in solving a crime. Many crimes are solved because someone has made very careful observations. Observations are things or events that you notice. A footprint, the smell of perfume, the sour taste of a drink, an unusual sound, or a warm log in a fireplace could provide clues to a crime. Normally, to make observations, you can use all your five senses. After making observations, you might be able to form a hypothesis about what happened.

Refer to page 12 of your notes Detective Skills Hypothesis A hypothesis is an educated guess. Conclusion If you were able to make more observations, you would be able to form a conclusion about the events that took place. A conclusion was the final outcome of an investigation; that is, what was found out.

i) Independent variables An independent variable is a one whose values are chosen by the experimenter. In other words, the values of these variables are independent of the participant's behaviour. For the independent variable to be manipulated, at least two levels must be present in an experiment. (Refer to Story in Pg 15) The most basic way to manipulate is by creating one experimental group (the group receiving the treatment) and a control group (exactly like the experimental group, except without the experimental treatment). The performances of the two groups in regard to the dependent measure are then compared to assess the effect of the independent variable. Refer to page 16 of your notes

ii) Dependent variables The variable whose value you observe and record in experimental designs is the called the dependent variable (or dependent measure). In other words, the dependent variable value depends on the behaviour of the participant, rather than being set by the experimenter. iii) Constant variable Those factors in the experiment that the scientist attempts to keep constant. Refer to page 15 of your notes

In a Typical Lab Exp To understand how to plan and carry out a scientific investigation, let’s try the following question: Step 1: Observation It is observed that ice cubes melt faster in hotter water. Step 2: Question A question is asked about the observation. “Does an ice cube melt faster in hot water?” Step 3: Hypothesis An ice cube would melt faster in hot water

In a Typical Lab Exp Step 4: Method Study all the information closely. For example, size of ice cubes, amount of water etc.

In a Typical Lab Exp (i) Variables The independent variable is the variable that you change and this will cause the dependent variable to change and this change is being observed. The rest of the variables that do not change are called constant variables. In this experiment: Independent Variable: Dependent Variable: Constant Variable: Temperature of Water Time taken by ice cube to melt completely 1)Size of Ice Cubes, 2) Size of Beaker, 3) Amount of water used

In a Typical Lab Exp (ii)Apparatus to Use We will need these pieces of apparatus and materials; two beakers of the same size, a measuring cylinder, a stopwatch, cooler water (tap water), hot water and two ice cubes of the same size, Measuring Cylinder, ice cubes, beaker and stopwatch. (iii)Procedure 1.Add 50 cm 3 of tap water to a measuring cylinder. 2.Pour the water into a beaker 3.Add one ice cube into the beaker of water 4.Using the stop-watch measure the time taken for the ice cube to melt completely. 5.Repeat steps 1 to 4 for another 3 sets of readings.

In a Typical Lab Exp Step 5: Analyse your Results

In a Typical Lab Exp Step 6: Conclusions From the results, we can have the following conclusion: An ice cube melts faster in hotter water than cooler water

Refer to page 17 of your notes Pierre’ 1 st Experiment Mixture of Special Vitamins

Refer to page 17 of your notes Pierre’ 2 nd Experiment Food A: Special Vitamin + Commercial Dog Food Food A: Special Vitamin + Commercial Dog Food Collie Puppy Food B: Another type of Dog Food Food B: Another type of Dog Food Mutt

Refer to page 17 of your notes Pierre’ 3 rd Experiment Food A: Special Vitamin + Standard Dog Food Food A: Special Vitamin + Standard Dog Food Beagle Food B: Standard Dog Food Food B: Standard Dog Food Beagle

Refer to page 17 of your notes 1. What trait characterise a good scientist? How does Pierre demonstrate these traits? A good scientist must be willing to have their own ideas questioned, must have determination and patience. Pierre listened to his friends’ criticism on his experiments He showed determination by his willingness to carry on even after two failures. He showed patience as he took three long years to complete this experiment. 2. What was wrong with Pierre’s first food experiment? Pierre did not have a control dog to compare the results with.

Refer to page 17 of your notes 3. What two mistakes did he make in his second experiment? The two dogs are different and the commercial dog food they are given are different. 4. Why is a control important in a scientific experiment? A control is an experimental set-up with the absence of the independent variable. This ensures that the result of the experiment is due to the independent variables and not other factors.

Refer to page 17 of your notes 5. Which was the control dog and which was the experimental dog in Pierre’s third attempt? Dog B – control dog, Dog A – experimental dog. 6. Why is repeatability important in science? With more readings in repeated experiments, the average obtained will be more accurate and thus more reliable.

Refer to page 17 of your notes 7. What other kinds of experiments could you do to test Pierre’s conclusion about the effects of his dog vitamins? i. Find out the difference of the height between the dogs. ii. Create a number of tasks for the dogs to perform and see how many tests they pass iii. Perform the experiment again on other species of dogs.