Scientific method and measurement

The Scientific Method and Measurement

Page 1: Introduction

• Overview of the scientific method and its importance in scientific investigations.

Page 2: What Is Science?

• Science involves systematic research following specific steps known as the Scientific Method:

  • Observing and asking questions

  • Making inferences and forming hypotheses

  • Conducting controlled experiments

  • Collecting and analyzing data

  • Drawing conclusions

Page 3: Observing and Asking Questions

• Observations begin the scientific process:

  • Example: Marsh grass grows taller in certain locations than others.

  • This observation leads to scientific questioning:

    • Why does marsh grass grow to different heights in various places?

Page 4: Inferring and Forming a Hypothesis

• After observations, scientists make inferences based on prior knowledge.

  • Inferences can lead to developing a hypothesis:

    • A testable scientific explanation for a set of observations.

Page 5: Example of Inferring and Hypothesizing

• Researchers inferred limits to grass growth in specific areas:

  • Hypothesis: Growth limitation is due to a lack of available nitrogen.

Page 6: Designing Controlled Experiments

• Designing an experiment involves explaining how variables will change and measuring responses.

  • Examples of variables include temperature, light, time, and nutrient availability.

Page 7: Controlling Variables

• Only one variable should be changed during an experiment (independent variable); all others should be controlled (dependent variable).

• Controlled Experiments:

  • Involve comparing experimental results against controlled factors.

Page 8: Control and Experimental Groups

• An experiment typically includes a control group:

  • Same conditions as experimental group but not manipulated the same way.

  • Example: Grass samples with varying nitrogen exposure; control group receives no nitrogen.

Page 9: Example of Controlled Experiment Setup

• Research team selected comparable marsh grass plots divided into control and experimental groups:

  • Independent Variable: Application of nitrogen fertilizer.

  • Dependent Variable: Observed growth of marsh grass.

Page 10: Collecting and Analyzing Data

• Data from experimental observations is critical for drawing conclusions.

  • Two main types of data collected:

    • Quantitative Data: Numerical information.

    • Qualitative Data: Descriptive information.

Page 11: Quantitative Data

• Numerical data collected through counting or measuring:

  • Includes number of plants per plot, sizes, and growth rates.

Page 12: Qualitative Data

• Descriptive data that cannot be quantified:

  • For instance, observations of foreign objects in plots and growth orientation of grasses.

Page 13: Research Tools

• Visual representation (graph) indicates changes in grass height over time:

  • Example: Height of grasses over 1N Control through time (weeks).

Page 14: Sources of Error

• Importance of careful data set analysis and consideration of sample size:

  • Larger sample sizes increase analysis reliability and variation assessment.

Page 15: Drawing Conclusions

• Scientists use collected data as evidence to support or refute hypotheses:

  • Formulate valid conclusions based on data.

Page 16: When Experiments Are Not Possible

• Ethical considerations can restrict certain experiments, particularly on humans:

  • Explore past exposure to potential carcinogens instead of controlled experimentation.

  • Temporal limitations may also restrict experiments (e.g., events that occur infrequently).

Page 17: Performing Biological Investigations

• Scientists conduct investigations to study living organisms, including calculations and data collection.

  • Utilize the metric system for consistency in measurements.

Page 18: Scientific Measurement

• The metric system is a decimal-based setup:

  • Units are multiples of ten.

Page 19: Common Metric Units

• Length:

  • 1 meter (m) = 100 centimeters (cm), 1 kilometer (km) = 1000 meters.

• Mass:

  • 1 kilogram (kg) = 1000 grams (g).

• Volume:

  • 1 liter (L) = 1000 milliliters (mL).

• Temperature:

  • 0°C = freezing point, 100°C = boiling point.

Page 20: Basic Units

• Summary of basic metric units:

  • Length: meter

  • Mass: gram

  • Volume: liter

  • Temperature: Celsius

Page 21: Metric Prefixes

• Mnemonic for metric prefixes:

  • Kilo: 1000 meters (km)

  • Hecto: 100 meters (hm)

  • Deca: 10 meters (dam)

  • Base: 1 meter (m)

  • Deci: 0.1 meter (dm)

  • Centi: 0.01 meter (cm)

  • Milli: 0.001 meter (mm)

Page 22: Examples

• Example conversions:

  • 23 mm = _________ Hm

  • 15 Km = _________ cm

  • 0.46 dm = ________ m