Scientific Method 7th grade science Vocabulary Term Control Group Dependent variable Hypothesis Independent Variable Variables Held Constant Inference Definition The group in an experiment in which the independent variable is not manipulated; it is used to make comparisons. The factor in an experiment that is measured The result; there may be 1 or many. Your prediction of what you think will happen. The factor in an experiment which is different in the experimental groups; there can only be one in a valid experiment. Factors that remain the same between the control and experimental group. Drawing a conclusion from an observation
A student wanted to determine the effects of different colored lights on plant growth. To do this, she set up two experiments. She grew one plant under blue light and one under red light and gave each plant the amount of water shown. Plant Growth 1. At the end of the experiment, plant 1 grew 10cm and plant 2 grew 5cm. She concluded that plants grow better under red light. Comment on her conclusion. Variables Plant 1 Plant 2 Light Red Blue Temp 2. How could you improve her experiment? Use the data table to show the new variables in your redesigned experiment. Water Time Plant Six Steps of the Scientific Method *People Really Hate Elephants On Cars P- R- H- E- O- C- Problem Research Hypothesis Experiment Observation Conclusion
Six Steps of the Scientific Method 1. Problem- 2. Research- 3. Hypothesis- 4. Experiment- 5. Observation- 6. Conclusion- Question you want to answer Info you gather Prediction, what you think the answer to your problem is. Tests the hypothesis Data collected in the experiment Is the hypothesis correct? Examples of the six steps 1. Problem- 2. Research- 3. Hypothesis- 4. Experiment- Do rats grow larger if given Vitamin C? Learn about mice, vit C, their diet If mice are given vit C, then they will grow larger. 2 groups- 1 gets vit C, 1 doesn t 5. Observation- 6. Conclusion- Weigh mice after 2 weeks- Vit C mice weigh the same as non-vit C mice. Hypothesis is not correct.
Variables: Factors in an experiment Independent variable: The thing being tested Can only be one! The Cause Variables Held Constant: Factors that are NOT allowed to change. Dependent variable: Data you collect Variable you do NOT know at the beginning The Result
Experimental Group: Groups Has the independent variable in it. Control Group: A test run for comparison No independent variable Observations 1. Dependent variable- Results 2. Data- Measurements (graphs, data tables) 3. Quantitative Observation- 4. Qualitative Observation- 5. Inferences- Quantity Are measured Have a number Quality Not measured Made with senses Conclusions based on an observation Ex: Inferring a slug that has remained still for several house is dead.
Observations & Inferences Observations: Using your senses/tools to gather info. Quantitative Observation: Numerical, includes a tool. Ex: Mr. DuRoss weighs 500kg Qualitative Observation: Description of what is being observed. Ex: The lightning was bright Inference: Conclusion based on an observation Example: you leave the movie theater and see the ground is wet so you infer that it. Rained Read the situation below and determine if the following statements are observations or inferences. Situation: You walk into the gym on Friday morning, the bleachers are cluttered with paper cups and food wrappers. The scoreboard is still lit up and you can tell that your team won last night. It looks as though many people were here, and you missed a great game. Inference 1. There was basketball game last night. Observation 2. The score board is lit up. Inference 3. There were many people there. Observation 4. Paper cups are in the bleachers.
Write 5 Observations about the above picture, then right an inference about each observation. Observations: Inferences about the observations Sun is on the horizon Sunset 1. 2. 3. 4. 5. Observations/inferences
Look at the drawings of Tom and Joe below. Write O if the statement is an obs O 11. Tom is shorter than Joe. O 12. Joe has straight hair. O 13. Joe is not smiling. I 14. Tom is happy. O 15. Joe has one ear. I 16. Tom is very energetic. I 17. Joe is a good basketball player. I 18. Tom likes ice cream. O 19. Tom has curly hair. I 20. Tom has naturally curly hair. Identify: 1= Qualitative Observations 2= Quantitative Observations 1. 2 The test tube measures 7cm tall. 2. 1 The sulfur smells like rotten eggs. 3. 2 The heartbeat of the bird is 190 beats/minute. 4. 2 The density of water is 1 gram / cm 3. 5. 1 The book is heavier than the pencil. 6. 2 It took 25 minutes for the water to freeze. 7. 1 The lemonade tastes sweeter than the iced tea. Identify: O = Observation I = Inference 8. O You are in a classroom. 9. I If you study, you will receive an A+ on your science test. 10. O There is a computer in this room. 11. I Everyone that has a tattoo likes hard rock music. 12. I If you become a vegetarian, you will live longer.
JV Football Team Scientific Method The mothers of the New Hartford JV football team decided that they had had it with trying to get the stains out of their sons uniforms. They had decided to conduct their own investigation of stain removers. They washed 30 filthy uniforms with Spray N Wash. They also washed 30 equally filthy uniforms with Gain. They also washed another load of 30 uniforms without any stain remover. Each load of laundry was washed in the same washing machine, on the same cycle, with 120 0 F water, using equal amounts of stain remover. The mothers then looked at the washed uniforms to see how clean they were. 1.What is the problem? 2.What was the independent variable? Stain remover 3.What was the dependent variable? Which stain remover will remove the stains. How clean the jerseys were 4.List 2 variables held constant. Same washer, cycle, temp 5.What was the purpose of the load without any stain remover? Control group, for comparison Zing Candy Bars A candy manufacturer developed a new candy called Zing. The developers could not decide on a color for the wrapper so they decided to conduct a test to see which color the buyers liked best. They made 8000 (100gram) candy bars and wrapped 2000 in red wrappers, 2000 in blue wrappers, 2000 in green wrappers, and 2000 in brown wrappers. All the bars sold for $.75, had the same shape, and were placed in the same store display. At the right is the data for the results of the test sale. Color of wrapper Number sold Red 1223 Blue 802 Green 1761 Brown 1476 1.What is the independent variable? Color of wrapper 2.What is the dependent variable? # sold 3.What are 4 variables held constant? Size, shape, price, display
Tires & Gas Mileage Scientific Method: Using Data Tables A tire manufacturer tested 4 different types of tires to determine what effect they might have on gas mileage. He had four brand new identical cars each drive 10,000 miles at 55 mph with the same kind of gasoline. They were all driven on the same test track under the same weather conditions. This table shows the results. Type of Tire Gas Mileage (mpg) A1 19 B2 20 C3 19 D4 22 1.What was the independent variable in this test? Type of Tire 2.What was the dependent variable? Mileage 3.List 5 variables held constant. Age of tires, type of gas, same track, distance traveled, speed 4.From this data form a conclusion. D4 provides the best gas mileage Paper Towel Activity Some students decided to compare the soaking power of five brands of paper towels. A strip 15cm long x 3cm wide was cut for each brand. The strips were placed into 5 separate, but identical beakers. Each beaker contained 200mL of water. The strips were placed in the beakers at the same time and to the same depth. After 30 seconds, the height to which the water soaked up the strip was measured. The following data was collected: Brand A soaked up 4cm, Brand B soaked up 1.5cm, Brand C soaked up 3cm, Brand D soaked up 5cm, and Brand E soaked up 2.5cm. 1.Place the data in the table below: Brand A 4 B 1.5 C 3 D 5 E 2.5 Height of water (cm) 2. What was the independent variable? Brand of paper towels 3. What was the dependent variable? Height of water 4. List 4 variables held constant. Same beakers, depth, time span, amount of water
Earthworms: Data tables Adam wanted to study earthworms to see what type of soil they survive in best. He found 5 equal size boxes and placed different types of soil in each box. (Box A had clay soil, Box B had swamp soil, Box C had sandy soil, Box D had potting soil, and box E had compost.) He then placed a young worm in each box and placed a loose cover over each box to block out the light and keep the moisture in. He poured 20mL of water into each box everyday to keep the soil moist. Each day, he weighed the worms on a balance and recorded his data in a data table. At the end of 2 weeks, he compared the weights of the worms from start to finish. The following are his results. Box A s worm gained. 5 grams; Box B s worm gained.7 grams; Box C s worm lost.3 grams, Box D s worm gained 1.1 grams; and Box E s worm gained 1.4 grams. 1.Show Adam s data in a data table. (Include box letter, soil, # of grams +/-). Box Soil +/- A Clay grams +.5 B Swamp +.7 C Sand +.3 D Potting +1.1 E Compost +1.4 2. What is Adam s problem? Which type of soil do worms grow in best. 3. What is the independent variable? Soil type 4. List 3 variables held constant. Age of worm, amount of water, time 5. Name the dependent variable. Weight of worms 6. What other dependent variables could have Adam made? Length of worm, activity, lifespan A farmer wanted to know if music would make his chickens happier and thus lay larger eggs. He took 2 groups of chickens and placed a radio tuned to a music station in a pen with one group. The other group was placed in a pen with no music. 1.What is the independent variable? Music 2.What is the dependent variable? Size of eggs laid 3.Which is the control group? No music 4.List 4 variables that the farmer should hold constant. Same type of coop Same age of chicken Same amount of water Same type of chicken
A student wanted to determine if sunlight kept goldfish healthy. He made up 2 fish tanks that looked the same and had one goldfish in each. The goldfish were weighed. He placed one tank in a dark room and one in a room with a lamp constantly on. He made sure he cleaned both tanks regularly. He fed the fish in the lighted tank every day, but only fed the fish in the dark room every 3 days. After 4 weeks, he examined and weighed the fish in both tanks. The fish from the lighted tank was heavier and swam around more frequently than the fish in the dark fish tank. He determined that sunlight makes goldfish happy. 1.Sketch the experiment below: Include the lamp & feeding schedule. Experiment #1 Experiment #2 Fed every 3 days Fed everyday 2. List 3 variables held constant. Tank, type of fish, temp of water 3. What is the dependent variable? Mass of fish, activity of fish 4. What is the student s conclusion? Light makes fish happy 5. Is this a valid experiment? Explain. No, too many independent variables
The Mythbusters team uncovers the myth if you talk to your plants then they will grow better. The Mythbusters set up 7 different groups of pea plants. 2 groups were exposed to sweet talk talking. 2 groups were exposed to abusive talking. 1 groups were exposed to heavy metal. 1 groups were exposed to classical music. 1 group was exposed to silence. Identify: Independent Variable: Dependent Variable(s): 2. List as many variables held constant as you can. a) b) c) 3. a) Describe the Experimental Group. b) Describe the Control Group. 4. Mythbusters had a setback. The pea plants turned yellow. Was this a major set back for the experiment? Why? 5. Why did the Mythbuster team use recordings instead of having people talk to them? 6. What conclusion did the Mythbusters reach?