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Teaching the Metric System

Teaching the Metric System. For meaning and understanding. Sally B. Mitchell sallybchemistry.com. Identify the problem. Engineer a Solution to a problem with education. 7 years of research Writing to learn Re-teach teachers (keep an open mind). Numbers.

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Teaching the Metric System

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  1. Teaching the Metric System For meaning and understanding Sally B. Mitchell sallybchemistry.com

  2. Identify the problem

  3. Engineer a Solution to a problem with education • 7 years of research • Writing to learn • Re-teach teachers (keep an open mind)

  4. Numbers • How many ways can you express this number? • Three hundred million

  5. Normal Notation 300,000,000

  6. Scientific Notation 3 x 108

  7. Engineering Notation 300 x 106

  8. Metric Notation 300 M

  9. Ways to express quantities • Written notation (three hundred million) • Number notation (300,000,000) • Scientific notation ( 3 x 108) • Engineering notation ( 300 x 106) • Metric notation ( 300 M) • Infinite number of other ways ( 30 x 107)

  10. What is a metric prefix? • Quantity? • Number? • Symbol?

  11. Why do we even use prefixes? • Easier to write • Easier to say • Easier to manipulate • It is concise

  12. Do you know your prefixes? 10-1210-910-610-3100 103 1061091012 p n μ m k M G T

  13. Try another • 0.000 000 000 032 • Notice the spaces between groups of 3 numbers • 3.2 x 10-11 (Scientific Notation) • 32 x 10-12 (Engineering Notation) • 32 p (Metric Notation)

  14. What is the appropriate prefix for this quantity? • The time was 45,000,000,000 seconds • 45 Gs • The distance between the objects was 0.000 050 m • 50 μm

  15. Why change the prefix? • Yet, we assess the student’s ability to CONVERT from kilometers to nanometers on the first day of class! • Convert 2 km to nm • REALLY? Is this a conversion?

  16. Sound Mathematical Principles 2 x 103 m

  17. Multiplicative Identity and Multiplicative Inverse 2 x 103x ( ) 109 x 10-9 m

  18. Associative Law andLaw of Exponents (2 x 103 x 109 ) x 10-9 m 2 x 1012 x 10-9 m

  19. Substitution of Symbol 2 x 1012nm

  20. Check it ? 2 km = 2 x 1012nm

  21. Look at only the quantity ? 2 k = 2 x 1012 n 2 x 103 = 2 x 1012 x 10-9

  22. Calculate the density of radon gas at STP • Mass = 450 mg Volume = 50 mL • Express your answer in g/L • Density = 9 g/L

  23. 100 % confidence • Teach about numbers and different ways to express • Review Scientific Notation • Introduce Engineering Notation • Discuss prefixes • Remember to develop “Prefixes are symbols” • Challenge your students to express quantities using different symbols

  24. Remember • NO DIMENSIONAL ANALYSIS • No tricks • No centi • Groups of 3 (300,000,000 0.000 000 000 032)

  25. What is a MOLE? 6.02 x 1023 ? 602 x 1021 ?

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