Metric System

Homework

Key Concepts Thus Far What is science (and pseudoscience and non-science?)

What are the 6 characteristics of science? Be able to use PLORNT to analyze a claim.

Distinguish between physical and chemical properties. Identify variables in an experiment. Design a fair test. What are precision and accuracy?

How do we quantify precision? Be able to identify number of sig figs, and do arithmetic with the correct

number of sig figs. Be able to read an instrument to the correct number of sig figs.

How do we quantify accuracy? Be able to calculate percent error.

Objectives Know what units the metric system uses

for mass, length, area, volume, time, and temperature

Know the metric system prefixes Be able to convert a figure from one

prefix to another

Setting Standards What about your standard proved to be

a difficulty? What about a standard made it easier to

use? What made for an accurate standard? A precise one?

Setting Standards The metric system was designed to

handle these difficulties. It’s set up to be the easiest, most precise, and most accurate standard that we have. In science, we will always be using the

metric system.

Metric Standards What are all the different standards

you’ve ever heard of that are used to measure the length or distance of something?

Metric standard for length: Meters (m)

Metric Standards What are all the different standards

you’ve ever heard of that are used to measure the surface area of something?

Metric standard for surface area: Meters squared (m2) Think back to the lab: why is it m2?

Metric Standards What are all the different standards

you’ve ever heard of that are used to measure the volume of something?

Metric standard for volume: Liters (L) OR Meters cubed (m3) Think back to the lab: why is it m3?

Metric Standards What are all the different standards you’ve

ever heard of that are used to measure the amount of stuff in something?

Metric standard for amount of matter: Grams (g) Note: Mass is not the same thing as weight! This

becomes important when we start talking gravity and outer space.

Metric Standards The metric system uses seconds (s) as the

standard for time.

Metric system uses degrees Celsius (°C) or degrees Kelvin (°K) for measuring temperature. We’re supposed to use Kelvin, but really we

usually use Celsius.

Metric Standards Once again, shout it out! Metric

standard for Length Area Volume Mass Time Temperature

Metric Standards The metric system’s Power of Ten

addresses a problem many of you found in your Setting Standards lab: A good standard for measuring the room is

bulky and imprecise for measuring smaller shapes, and what’s good for measuring smaller shapes is tedious when measuring larger ones.

Metric System Prefixes

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are needed to see this picture.

Metric System Prefixes Write this whole thing in your notebook: Kids Have Dark Umbrellas During Cloudy

Mornings Kilo - 1000 (103) Hecto - 100 (102) Deka - 10 (101) (Unit) (100) Deci - .1 (10-1) Centi - .01 (10-2) Milli - .001 (10-3)

Metric System Prefixes Again! KHDUDCM stands for what?

Which is the large number end, which is the small number end?

Practice If each of these is a measurement in meters,

tell me which prefix would be best to turn the measurement into: 140 .05 5600 80 .003 2

Practice If each of these is a measurement in meters,

tell me which prefix would be best to turn the measurement into: 140 -> Best to turn into hectometers .05 -> Best to turn into centimeters 5600 -> Best to turn into kilometers 80 -> Best to turn into dekameters .003 -> Best to turn into millimeters 2 -> Best to leave as meters

Converting Prefixes Suppose that you have a number with

one prefix, like millimeters, and you want to know how many meters it is.

How can I turn 50 millimeters into its equivalent in meters? What have you learned in math, or in

middle school science?

Converting Prefixes 1. Remember KHDUDCM. Locate your

starting prefix on the scale, and your finishing prefix.

2. Not counting your starting prefix letter, count how many letters are in between the two. Ex: From M to U is three. From H to C is

four. Etc.

Converting Prefixes 3. Hop the decimal place that many

digits in the same direction as your movement along the letters. Ex: If you counted from K to U, you’ll move

the decimal place to the right. If you counted from M to C, you’ll move the decimal place to the left. Etc.

Converting Prefixes In action: let’s turn 700 millimeters into

dekameters.

1. On KHDUDCM, the starting prefix is M, the finishing prefix is the farthest D.

2. That’s a count of four.

Converting Prefixes In action: let’s turn 700 millimeters into

dekameters.

3. The decimal place starts out at the end of the number. Hopping it four places to the left (because the letters moved to the left), we get… .07 dekameters.

Converting Prefixes Take whiteboards Write KHDUDCM at the top

Group practice

More Practice Write a five question quiz for another table on

changing metric system prefixes. One partner writes the quiz paper, the other

partner writes the answer key.

Give them your quiz, and you take theirs.

Then, check answers.