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INFORMATION

This lab introduces the concept of scientific inquiry and the two approaches to science: discovery science and hypothesis-based science. The lab also covers experimental design, variables, controlled experiments, and the use of scientific notation and the metric system in scientific inquiry.

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INFORMATION

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  1. INFORMATION • COLLECT: Pre-lab #2 • LAB QUIZ #1 • MICROWORLDS • Questions? • Four entries due by end of lab next week

  2. Lab 2: Process and Tools of Scientific Inquiry

  3. Two Approaches to Science DISCOVERY SCIENCE • No experiments • Based on observations • Inductive reasoning – general principles derived from large number of specific observations EXAMPLE: All living things are composed of cells

  4. Two Approaches to Science HYPOTHESIS-BASED SCIENCE • Involves carefully planned experiments • Based on observations • Deductive reasoning – takes a general statement and extrapolates specific results we would expect

  5. Experimental Design VARIABLES: things that might change during the experiment • INDEPENDENT VARIABLE: what you are changing in the experiment (what you’re testing) • DEPENDENT VARIABLE: what you are measuring • CONSTANT VARIABLES: things that are the same between your groups The DEPENDENT VARIABLE depends on the INDEPENDENT VARIABLE

  6. Experimental Design – Controlled Experiments You generally have two groups: • CONTROL GROUP (CONTROL TREATMENT): The group you are going to compare to; the one you don’t do anything to • EXPERIMENTAL GROUP: The group(s) on which you are testing something

  7. Controlled Experiment Control Group Experimental Group WATER WATER + FERTILIZER

  8. Only once? • How many times should you do an experiment? • How should you test multiple samples?

  9. Sampling Error • Draw 1 jelly bean? • Draw 10 beans? • Draw 100 beans? • Draw all the beans? • SAMPLE SIZE: The number of samples, the more the better

  10. Lab: Black Box Experiment • Identify what is contained in your box without peeking!

  11. Scientific Notation and the Metric System – Appendix A • SCIENTIFIC NOTATION: More compact form of a very large or very small number • The distance to the Sun's nearest neighbor Alpha Centauri is greater than 10,000,000,000,000,000 m.

  12. Tools for Scientific Inquiry: Scientific Notation • Tells you how many times you must multiply or divide by 10 to get the number • A number x 10B • The distance to the Sun's nearest neighbor Alpha Centauri is greater than 1 x 1016m.

  13. Tools for Scientific Inquiry: Scientific Notation • 1 x 1016 positive number = multiply by 10 10000000000000000 • 1 x 10-16m negative number = divide by 10 0.0000000000000001

  14. Tools for Scientific Inquiry: Scientific Notation • MULTIPLICATION: Add the exponents EX: (2 x 104)(3 x 105) = 6 x 109 20000*300000 = 6000000000 • DIVISION: Subtract the exponents EX: (6 x 109) / (3 x 105) = 2 x 104 6000000000 / 300000 = 20000

  15. Tools for Scientific Inquiry: The Metric System

  16. Metric System • Science uses the metric system. • The metric units are: • meter for distance (measurement from one point to another) • liter for volume (ie, the space that 1 liter of water occupies) • gram for mass (weight), • and degree Celsius for temperature. • metric units do not advance like English: grain, ounce, pound, ton • they advance using prefixes & powers of ten

  17. Metric how-to • It’s all about powers of TEN

  18. Metric System Metric units are convertible.  • 1 cubic centimeter (or 1 cc) of water is equal to 1 milliliter (ml) which is equal to 1 gram of water at sea level.  • This does not work if water is not the material of study!

  19. Basic Metric Measurements • You will measure water in a cylinder, tends to stick to the sides, especially with glass.  • This makes the meniscus, the boundary between the air and the water, curved.  • The correct way to read it is to read it from the bottom of the meniscus!

  20. Converting Units • Set up equations to cancel out units 200 m = cm 200 m * 1 x 102 cm = 20000 cm = 2 x 104 cm 1 m • THINK ABOUT YOUR ANSWER: Should there be more cm than m? Should there be fewer? • DOES YOUR ANSWER MAKE SENSE??

  21. Practice Question 250 cm = • Meters? • Millimeters?

  22. Measurements Accurate Precise How consistently can a measurement be reproduced? • How close is the measurement to the true value?

  23. Measurements • Use a measuring tool that is close to the measurement you want to make

  24. Lab: Appendix A - Measuring • Read the information in the lab • Practice measuring with a pipette, graduated cylinder, balance, ruler/meter stick • Be able to answer the questions in the Study Guide in preparation for the quiz next week!

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