Chapter 1: The Nature of Science

1. Chapter 1: The Nature of Science 1.1 : The Methods of Science 1.2 : Standards of Measurement 1.3 : Communicating with Graphs

2. 1.1 The Methods of Science

3. Science • A method for the study of the natural world • A process that uses observation and investigation to gain knowledge about events in nature

4. Categories of Science • Life Science – involves the study of living things • Earth Science – involves the study of Earth and Space • Physical Science – involves the study of matter and energy

5. Scientific Investigation • Investigations can be done many different ways: • Observations – simply looking at/watching an object(s) and recording what is taking place • Experiments – testing the effect of one thing on another

6. Scientific Method

7. Scientific Method • An organized set of 6 steps that scientists use to guide their investigations • State the problem – Why/How? • Gather Information – Learn as much as possible about the problem • Some sources of scientific information are not accurate • Form a hypothesis – a possible explanation for a problem using what you know/observe • Test the hypothesis – Observations/Experiments

8. Scientific Method • When testing the hypothesis: • Independent variable – the variable “you” change to see how it will effect the dep. variable • Dependent variable – value changes according to changes in other variables. [Cause and Effect Relationship] • Constant – A factor that does not change • Control – the standard by which the experimental results can be compared All other variables should be help constant so that 1 variable is tested at a time

9. Scientific Method • Analyze Data– all data gained in the investigation should be recorded, not just the data you like or think is right • This data can be organized into tables and graphs so that it is easier to read • Draw conclusions – Ask yourself if the data that you gained from the study supports or does not support your hypothesis • If your hypothesis is supported, you must repeat your study to further prove that it is supported • If your hypothesis is NOT supported, you may want to go back and reconsider the hypothesis One should conduct repeated trials to limit random error in measurements

10. Scientific Bias • Bias occurs when what the scientist expects changes how the results are viewed • Findings are supportable when others can do the same experiment and get the same results

11. Models • Models represent an idea, event, or object to better help people understand it • Why create models? • Models are created in cases where objects are • Too large (ex. The solar system) • Too small (ex. Animal cells, the atom) • Too dangerous (ex. Computer models of nuclear explosions)

12. Scientific Theory vs. Scientific Law A theory can be used to explain a law!

13. Activity • Get into groups of four • On a sheet of paper to be turned in, put: • The problem • Information gathered (if applicable) • Form a hypothesis • How you would test your hypothesis (Include dependent/independent variables, constant, control) • How you would analyze the data • Draw a conclusion and decide whether you support your hypothesis or not

14. EXAMPLE • Problem – (Stated as a question) Does the temperature of a room affect the # of dreams you have? • Hypothesis • An educated guess • A possible answer to the problem • My hypothesis: If the room is hot, a subject will have more dreams

15. EXAMPLE 3. Designing an Experiment • Control – 74° F • Constants – type of clothing, type of mattress, lighting, same type of meal before bed, etc. • Independent variable - 45° F, 85° F, 95° F • Dependent variable – Number of dreams recorded the next morning, or recording of brain activity

16. EXAMPLE 4. Analyzing the Data Data Table – temperature vs. number of dreams ex. I could then place the information on a graph

17. EXAMPLE 5. Draw a conclusion My data supports my hypothesis because the number of dreams increased as the temperature of the room increased Next, I would repeat the experiment several times to see if I get the same results

18. 1.2 Standards of Measurement

19. Units and Standards • Standard – an exact quantity that people agree to use to compare measurements • Ex. Using Feet/Hands to measure distance across the room • A measurement MUST include a number and a unit • English • Metric • SI

20. International System of Units (SI) • Le Systeme Internationale d’Unites • SI standards are accepted and understood by scientists around the world • Each type of measurement has a base unit • Ex. Meter is the base unit for length, Liter for volume, Gram for mass, second for time, kelvin for temp. • Based on multiples of 10, prefixes are used with the names for the units to indicate the multiple of 10 • ex. kilo – 1,000, so 1 kilometer = 1,000 meters

21. SI Base Units and Common SI Prefixes

22. Dimensional Analysis • Sometimes quantities are measured using different units • To convert from one quantity to another conversion factors are used 1,000 mL/1 L = 1 • Ex: Convert 1.225 L to mL • Ex: Convert 3,075 mm to cm • Ex: Convert11 cm to mm • Ex: Convert 1 kg to g

23. Measuring Distance Length – the distance between two points • Choosing a Unit of length – the size of unit depends on what you are measuring • What measurement would you use to measure the length of a pencil? • How about the distance to your house? By using the correct unit, you avoid large numbers and numbers with many decimal places

24. Measuring Volume • Volume (solid object) – the amount of space occupied by an object V = l x w xh = units3 • Volume (liquid) – the capacity of the container that holds the amount of liquid 1 mL = 1 cm3 (Easy to measure if you remember this when you use a graduated cylinder) Ex. Convert 1.5 L to cm3

25. Measuring Matter • Mass – a measurement of the quantity of matter in an object (golf ball vs. ping pong ball) • Density – the mass per unit of volume of a material Objects may have the same volume such as cylinders of aluminum, wood, or plastic Even though they occupy the same space, the matter within them is packed differently Density = Mass/Volume • Derived Unit – a unit obtained by combining different SI units (g/cm3) / an SI unit multiplied by itself (m3)

26. Measuring Time & Temperature • Temperature is a measure of how hot or how cold something is Celsius – common for measuring temperature Fahrenheit Kelvin– the SI unit of temperature - 0 K is the coldest possible temp (absolute zero) - Doesn’t use degrees - Celsius = (F – 32)/1.8 - Kelvin = Celsius + 273

27. 1.3 Communicating with Graphs

28. Graphs • A graph is a visual display of information or data • Graphs make it easier to see patterns or trends in experimental data Line Graphs Bar Graphs Circle Graphs

29. Line Graphs • Show any relationship where the dependent variable (y-axis) changes due to a change in the independent variable (x-axis) • Best for showing continuous data • Can you show more than one event on the same graph? • Yes! As long as the relationship between the variables is the same

30. Line Graphs *minutes after turning on heat

31. Constructing Line Graphs • Choose a scale with intervals on each axis in equal measurements • Use the x-axis for the independent variable, just long enough to fit data • Use the y-axis for the dependent variable with 2 data points more than is needed • Use the same unit of measurement • May need to show a break in the axis if your data is very large

32. Implications of Graphs • Direct proportion – one variable increases as the other increases OR one variable decreases as the other decreases • Usually a straight line with a positive slope • Shows a direct relationship that changes at a constant rate • What would a greater slope mean?

33. Implications of Graphs • Inverse proportion – the product of two quantities is a constant • EX. V = f λ • Frequency and wavelength are inversely proportional • As one quantity increases, the other decreases

34. Bar Graphs • Bar graphs are useful for comparing information collected by counting • Each bar represents a quantity counted at a particular time • Where should you plot independent and dependent variables? • Points are not connected because the data is not showing how a change in one variable affects the other

35. Bar Graphs

36. Circle Graphs • A circle (pie graph) is used to show how some fixed quantity is broken down into parts • Circle represents the total • Slices represent the parts, usually a percentage of the total

37. Making a Circle Graph • Start with the total of what you are analyzing • For each type, divide that amount by the total • Multiply that decimal by 360° to determine the angle • Ex. Total buildings = 72 18 of the buildings use steam 18 ÷ 72 × 360° = 90° Then, you would measure 90° on the circle to show 25%

38. Technology • Technology is NOT the same as science • Technology is the application of scientific discoveries to meet human needs and goals through the development of products and processes • Engineering focuses on these processes by applying science to make products and design processes

39. Technological Design • 4 Stages of Technological Design • Problem identification • Solution design of a process or product • Implementation • Evaluation • Requirements • Cost and time effectiveness • Materials that meet criteria (price, avaiblity, durability, not harmful, etc.) Benefits must exceed the risks

40. Scientific Investigation vs. Technological Design

41. Science Labs and Safety Procedures

42. Labs • In science labs, one uses various instruments to conduct investigations • You must be able to identify and know how to use certain instruments • You must always PUT SAFETY FIRST!!!

43. Graduated Cylinder – used to measure the volume of a liquid • Meniscus – the curve at the tip of a liquid in a graduated cylinder • Measurements are read from the BOTTOM center of the meniscus

44. Thermometer – a device that measures temperature

45. Bunsen Burner Beaker Erlenmeyer flask Funnel Pipette

46. Measurements • The last digit recorded is always estimated • The more decimals in the recorded measurement, the greater the precision of the instrument • EX. A 100 mL graduated cylinder marked in 1 mL increments measures exactly to the ones place A 10 mL graduated cylinder marked in 0.1 mL increments can be read exactly to the tenths place Which graduated cylinder is more precise?

47. Precision and Accuracy • Precision – a measure of the degree to which measurements made in the same way agree with one another • Accuracy – the degree to which the experimental value agrees with the true or accepted value • It is possible to have high precision with low accuracy if the same error is involved in repeated trails of the experiment

48. Precision and Accuracy

49. Lab Safety • Personal Safety – • Follow only designated lab procedures • Understand safety symbols • Wear proper clothing/shoes • Wear proper protective equipment (goggles, aprons) • Tie back loose hair • No eating/drinking • Use proper techniques for smelling, etc.

50. Lab Safety • Work area safety – • Keep work area clear, uncluttered • Turn off burners/hot plates when leaving lab • Know locations and proper use of the fire extinguisher, safety blanket, eyewash station, emergency shower, first aid kit • Disconnect electrical devices • Clean up • Report incidents, spills, etc. to teacher IMMEDIATELY!