The Scientific Method

1. The Scientific Method Mr. Luis A. Velazquez

2. What is the scientific method? • Is a step by step process to understand nature. • Scientists use an experiment to search for cause and effect relationships in nature. • In other words, they design an experiment so that changes to one item cause something else to vary in a predictable way.

3. What are the steps in the scientific method? • Define the problem • Gather information • Make an hypothesis • Test your hypothesis • Review your results • Make a conclusion

4. What are variables? • In an experiment these changing quantities are called variables, and an experiment usually has three kinds: • independent • dependent • control

5. The control variable • Controlled variables are quantities that a scientist wants to remain constant, and he must observe them as carefully as the dependent variables. Why? • Most experiments have more than one controlled variable. • Some people refer to controlled variables as "constant variables."

6. The Independent Variable • The independent variable is the one that is changed by the scientist. • In an experiment there is only oneindependent variable.

7. The dependent variable • The dependent variable changes in response to the change the scientist makes to the independent variable. • The number of dependent variables in an experiment varies, but there is often more than one.

8. Examples: • “For example, if you open a faucet (the _________ variable), the quantity of water flowing (__________ variable) changes in response-the water flow increases.”

9. How to identify the dependent variable? • To be predicted • The response variable • The outcome • A variable that is not under the experimenter's control.

10. Dependent One or more Output Response var Results and data Not controled Effects Independent Only one Input Manipulated var Is under the control of the Experimenter Cause Difference between Variables

11. How to identify the independent variable? • The cause • The input • The manipulated variable • The variable that is changed on purpose in an experiment.

12. if we want to measure how much water flow increases when we open a faucet, it is important to make sure that the water pressure (the controlled variable) is held constant. • That's because both the water pressure and the opening of a faucet have an impact on how much water flows. • If we change both of them at the same time, we can't be sure how much of the change in water flow is because of the faucet opening and how much because of the water pressure. • Most experiments have more than one controlled variable.

13. The SI Unit System Mr. Luis A. Velazquez

16. Prefix • Kilo 10x 10 x 10 = 1000 = 103 • Hecto 10 x 10 = 100 = 102 • Decka 10x1 = 10 = 101 • deci 1/10 = 0.1 = 10-1 • centi 1/100 = 0.01 = 10-2 • milli 1/1000 = 0.001 = 10-3 1x1 = 1 = 100

17. How to remember? K • King • Henry • Died • Drinking • Chocolate • Milk H Basic unit D d mass, length, volume c m

18. Kilo Left Hecto Decka Basic Unit Grams, Liters, meter deci centi Right milli

19. Practice Problems Kilograms are bigger than Grams So you need to multiply this means you move the decimal to the right How many times? 5 Kg =_______ g 5000 3 Answer 5000

20. Practice Problems centigrams are smaller than grams So you need to divide this means you move the decimal to the left How many times? .045 cg =_______ g .00045 2 Answer .00045

21. Practice Problems Dekagrams are bigger than grams So you need to multiply this means you move the decimal to the right How many times? 36 Dg =_______ g 360 1 Answer 360

22. Practice Problems milligrams are smaller than Kilograms So you need to divide this means you move the decimal to the left How many times? 7 mg =____________ Kg 0.000007 6 Answer 0.000007

23. Practice Problems Liters are bigger than milliliters So you need to multiply this means you move the decimal to the right. How many times? 9 L =_______ mL 9000 3 Answer 9000

24. Answer tofollowing Problems • 35L = .035KL • 46 g = .46Hg • 0.000015mg = .0000000015Dg • 9.53 mm = .00953 m • 7.908 cL = .07908 L • 0.521 Hm = 5210cm

25. 35L = .035 KL Liter are smaller than Kiloliters so you divide or move your decimal to the left. You move your decimal to the left three times The answer is .035 KL

26. 46 g = 0 .46 Hg Grams are smaller than Hectograms so you divide or move your decimal to the left. You move your decimal to the left two times . The answer is 0.46Hg or .46 Hg

27. 0.000015mg = .0000000015 Dg milligrams are smaller than Decagrams so you divide or move you decimal to the left. You move your decimal to the left four times. The answer is .0000000015 Dg

28. 9.53 mm = .00953m millimeters are smaller than meter so you divide or move you decimal to the left. You move your decimal to the left three times The answer is .00953 meters

29. 7.908 cL = .07908L centiliters are smaller than Liters so you divide or move you decimal to the left. You move your decimal to the left two times. The answer is .07908 Liters

30. 0.521 Hm = 5210 cm Hectometer are bigger than centimeters so you multiply or move you decimal to the right. You move your decimal to the right four times. The answer is 5210 cm