The SI System

1. The SI System or How to Know “How Much?”

2. The Metric System • Officially called the SI System • Based on increments of 10 (one decimal place or zero) • A good measurement has a number and a unit • Prefixes on the unit name tell you how many zeroes to put before or after a number • Used in every country around the world except the USA and Báhrain • The official measurement system of the USA since the late 1800s

3. Why you don’t already know the Metric System Your parents didn’t know it No incentive for companies to switch You are still being taught the Imperial System through everyday experiences - Recipes - Consumer goods There is a slow, steady inclusion process

4. Base Units • Base units are defined by only one measurement

5. Length • Distance from one point to another • Meters(m) are the base units (a little longer than a yard) • For smaller items, centimeters (about one knuckle), and millimeters (the thickness of a dime) are used

6. Mass • Amount of substance (number of particles) in an object • Gram(g) is the base unit • It is too small for some common measurements (about 1 paper clip of matter) • Usually use the kilogram(kg) for basis of comparisons • A kilogram is a little more than 2 pounds

7. Time • How long it takes for something to happen • Also called “Time Elapsed” or “Elapsed Time” • Seconds(s) are the base unit • Can lead to large numbers (1hr = 3600s)

8. 20 What would you use to measure the length of your arm? • Liters • Meters • Grams • Grams/Milliliter

9. 20 What would you use to measure how much sugar is in one teaspoon? • Liters • Meters • Grams • Kilograms

10. 20 What would you use to measure how much you weigh? • Liters • Meters • Grams • Kilograms

11. 20 What would you use to measure the width of the room? • Liters • Meters • Grams • Grams/Milliliter

12. Participant Scores

13. Derived Units of the SI System • Derived units are defined by two or more measurements • Volume • Amount of space taken up by a substance • Liters (L) are the base units (a little more than a quart) • Liters are too large for some measurements, so milliliters (mL) are often used

14. 20 What would you use to measure how much water is in a pool? • Liters • Meters • Grams • Grams/Milliliter

15. More Derived Units • Density • Amount of matter in an object divided by the space taken up by the object • “How much stuff is in how much space” • Usually expressed in grams per milliliter (g/mL) for smaller amounts • Expressed in kilograms per liter (kg/L) for larger amounts • THE NUMBER DOES NOT CHANGE

16. SI Prefixes • Used to show a number of base units • Think of them as coefficients (multipliers) • Easy to convert by sliding the decimal

17. SI Prefixes • From the largest to the smallest • kilo- hecto- deka- BASE deci- centi- milli- • 1000 100 10 1 1/10 1/100 1/1000 • “King Henry died by drinking chocolate milk.” • Put your finger on the unit you have, move it to the unit you want • Move your decimal the same number of places in the same direction that your finger moved

18. Testing your knowledge… • Answer the five questions… • Use the “Metric Ruler” to slide the decimal to get the desired units… • Ready?

19. 20 What is 25mm in m? • 2.5m • 0.25m • 0.025m • 0.0025m

20. 20 How many grams are 1.12kg? • 112g • 0.00112g • 0.112g • 1120g

21. 20 How many Liters are 591mL? • 0.591L • 59.1L • 0.059L • 5.91L

22. 20 What is 2.5cm in mm? • 250mm • .25mm • 25mm • 0.025mm

23. 20 0.355L is how many mL? • 3.55mL • 35.5mL • 355mL • 3550mL