Page 3 What is Science?. A. Definition 1. Science is investigating and understanding the natural world 2. It is the ability to explain events in the natural world 3. It is the ability to use those explanations to make useful predictions B. Science deals only with the natural world C. Scientists 1. collect and organize information in a careful, orderly way, looking for patterns and connections between events 2. Scientists propose explanations that can be tested by examining evidence 3. Science is an organized way of using evidence to learn about the natural world D. Goal 1. To understand the laws to give explanations for events that occur 2. Aims to use the explanations to find & understand patterns 3. Aims to use the explanations to make useful predictions about natural events
Page 4 Scientific Method The scientific method is: A series of steps used by scientists to solve a problem or answer a question. The Steps to the Scientific Method 1.Observation / Asking a Question 2.Form a Hypothesis 3.Design a Controlled Experiment 4.Record and Analyze Results 5.Draw Conclusions
Page 5 How is Science Done? B. Process 1. Observation a. Process of noticing and describing events in a careful, organized way b. Leads to questions and inferences 2. Hypothesis a.possible explanation for a set of observations or a possible answer to a scientific question
Page 6 What is a hypothesis? 1.A guess 2.A joke 3.An educated guess 4.A fact
Page 7 Step 1: Observation / Asking a Question Step 2: Form a Hypothesis A problem or a question must first be identified. How much water can a root hair absorb? Why does a plant stem bend toward the light? What effect does temperature have on heart rate? Hypothesis A possible explanation to the question or problem. It is simply a prediction and has not yet been proven or disproven. It must be stated in a way that is testable. A statement is considered “testable” if evidence can be collected that either does or does not support it. It must be stated in a way that is testable. A statement is considered “testable” if evidence can be collected that either does or does not support it.
Page 8 Which is NOT true about the observation step? 1. It’s unorganized 2.It’s a process of noticing events 3.It leads to questions 4.It leads to inferences
Page 9 How is Science Done? 3. Experiment a.Once a hypothesis is made one must test it using controls and variables b. Controlled experiment 1. An experiment in which only one variable is changed 2. Done to be able to see what causes the change c. Independent variable 1. The variable that is changed d. Dependent variable 1. The variable that is observed and changed because of the modifications of the independent e. Control group 1.Group in the experiment that is exposed to the same condition as he experiment group except for one independent variable **** test must have a large sample to get a true picture of results of the experiment
Page 10 4.Collect & Analyze data a. The information collected when doing an experiment b.The data that has been collected must be organized and analyzed to determine whether the data are reliable c. Two types 2. Quantitative data a. numbers and are obtained by counting or measuring. 1. Qualitative data a. descriptions and involve characteristics that cannot be counted d. Does the data support or not support the hypothesis
Page 11 What’s the importance of a control in the experiment? 1.To confuse others 2.To show change 3.To show what happens
Page 12 What’s the independent variable? 1.Something observed 2.Something that is changed 3.Something added to confuse others 4.Something to throw off the experiment
Page 13 What is the dependent variable? 1. Something added to confuse others 2.Something observed 3.Something to throw off the experiment 4.Something that is changed
Page 14 5. Drawing a conclusion a.The evidence from the experiment is used to determine if the hypothesis is supported or not supported, change the hypothesis or to draw a valid conclusion b.Experiments must be repeated over and over. When repeated, the results should always be the same before a valid conclusion can be reached. c. Theory 1.A theory may be formed after the hypothesis has been tested many times and is supported by much evidence. 2.A broad and comprehensive statement of what is thought to be true. 3. A theory is supported by considerable evidence.
Page 15 Example: In order to test the effectiveness of a new vaccine, 50 volunteers are selected and divided into two groups. One group will be the control group and the other will be the experimental group. Both groups are given a pill to take that is identical in size, shape, color and texture. Describe the control group. Describe the experimental group. What variables are kept constant? What variable is being changed? Even though the volunteers are given identical looking pills, the control group will not actually receive the vaccine. This group will receive the vaccine. The size, shape, color, and texture of the pill. Whether or not the pill contains the vaccine.
Page 16 There are two variables in an experiment: a) The independent variable is the variable that is deliberately changed by the scientist. b) The dependent variable is the one observed during the experiment. The dependent variable is the data we collect during the experiment. This data is collected as a result of changing the independent variable. c) In the above example, what is the independent variable? It is the addition of the vaccine to the pills that were given to the volunteers. d) In the above example, what is the dependent variable? The observed health of the people receiving the pills.
Page 17 You want to determine the effects of a certain fertilizer on the growth of orchids grown in a greenhouse. Materials that are available to you include: greenhouse, 100 orchid plants, water, fertilizer, and soil. You want to know if the orchids will grow best with a weak concentration of fertilizer, a medium concentration of fertilizer, or a high concentration of fertilizer. How will you design an experiment to test different concentrations of this fertilizer? State your hypothesis: Possible answer: I predict that the orchids will grow best with a medium concentration of fertilizer.
Page 18 Here is one possibility: The 100 plants will be divided into 4 groups as follows: The plants will be watered daily. Over a period of a month, the plants will be measured to see which ones grew the tallest. Group 1: 25 plants will receive plain water. Group 2: 25 plants will receive a weak concentration of fertilizer. Group 3: 25 plants will receive a medium concentration of fertilizer. Group 4: 25 plants will receive a high concentration of fertilizer.
Page 19 Control GroupExperimental Group What is the control group in this experiment? The control group consists of the 25 plants that are receiving plain water. What is the experimental group in this experiment? The experimental group consists of the 75 plants that are receiving various concentrations of fertilizer.
Page 20 In a “controlled experiment”, all variables must be kept constant except the one variable that is being changed. What variables must be kept constant in this experiment? All plants must receive the same amount of fluid each day. All plants are grown in pots of equal size. All plants are grown at the same temperature. All plants receive the same amount of sunlight. What variable is being changed in this experiment? The variable being changed is the amount of fertilizer received by each group of plants. What variable is being changed in this experiment? The variable being changed is the amount of fertilizer received by each group of plants.
Page 21 Group 1 (Control Group): Grew to an average height of 15 cm. Group 2 (Weak conc.): Grew to an average height of 35 cm. Group 3 (Medium conc.): Grew to an average height of 28 cm. Group 4 (High conc.): Grew to an average height of 10 cm. Is your hypothesis supported or disproved by these results? We hypothesized that the orchids would grow best with a medium concentration of fertilizer. The results do not support this. The results disprove our hypothesis. Is your hypothesis supported or disproved by these results? We hypothesized that the orchids would grow best with a medium concentration of fertilizer. The results do not support this. The results disprove our hypothesis.
Page 22 Group 1 (Control Group): Grew to an average height of 15 cm. Group 2 (Weak conc.): Grew to an average height of 35 cm. Group 3 (Medium conc.): Grew to an average height of 28 cm. Group 4 (High conc.): Grew to an average height of 10 cm. What is your conclusion based on these results? Orchids grow best with a weak concentration of fertilizer. At medium to high concentrations, plant growth is inhibited. What is your conclusion based on these results? Orchids grow best with a weak concentration of fertilizer. At medium to high concentrations, plant growth is inhibited.
Page 23 Analysis Questions Why is it important to repeat the experiment many times? Experiments should be repeated to see if the same results are obtained each time. This gives validity to the test results.
Page 24 Analysis Questions Why is it so important that a scientist accurately describes the procedure used in the experiment? It allows other scientists to repeat the experiment and verify the results.
Page 25 When doing a controlled experiment, why must all the variables but one be kept constant throughout the experiment? 1.So there’s no confusion 2.To know which variable is responsible for the results 3.Neither of the above 4.Both A & B Countdown 15
Page 26 What is a theory? 1.A fact 2.Statement of what is believed to be true 3.A hypothesis 4.An education guess Countdown 15
Page 27 The Strange Case of BeriBeri In 1887 a strange nerve disease attacked the people on the Dutch East Indies. The disease was beriberi. Symptoms of the disease included weakness and loss of appetite, victims often died of heart failure. Scientists thought the disease might be might be cause by bacteria, They injected chickens with bacteria from the blood of patients with beriberi. The injected chickens became sick, however, so did a group of chickens that were not injected with bacteria. One of the scientists, Dr. Eijkman, noticed something. Before the experiment all the chickens had eaten whole-grain rice, but during the experiment, the chickens were fed polished rice. Dr. Eijkman researched this interesting case and found out the polished rice lacked thiamine, a vitamin necessary for good health. 1.State the problem 2. What was the hypothesis? What causes BeriBeri Caused by bacteria
Page 28 3.How was the hypothesis tested? 4. Should the hypothesis be supported or rejected on the experiment? 5. What should be the new hypothesis and how would you test it? Injected the bacteria from the blood of infected people into the chickens rejected Caused by the lack of thiamine
Page 29 6. Identify the problem 7. What was Flemming’s hypothesis? 8. How was the hypothesis tested? Took the mold to the nutrient broth; next removed the mold then finally put broth on bacteria 9. Should the hypothesis be supported or rejected on the experiment? 10.This experiment led to the development of what major medical advancement? How is mold killing bacteria? Thought mold produces a substance that kills the bacteria support penicillin
Page 30 Different rose bushes are grown in a greenhouse for two month. The number of flowers on each bush are counted at the end of the experiment. IV - DV - Type of rush bush Number of flowers
Page 31 You water three sunflower plants with salt water. Each plant receives a different concentration of salt solution. A fourth plant receives pure water. After a two week period, the height is measured. IV -- DV -- CG -- Concentration of salt water height Pure water