The Metric System and Simple Metric Conversions

8th Grade Earth and Space ScienceMrs. Liberatore

Why Use the Metric System?• Scientists need to understand each other.

• Creates a consistent form of measurement.

• Everywhere in the world (except the U.S.) uses the metric system.

The Metric System• Also called the “SI System” – International

System of Units

• Based on 10’s

• Prefixes change the size of the unit

• There is a base unit for each type of measurement.

Base Units and Important Prefixes• Base Units:

– Length – meters (m)– Area – square meters (m2)– Mass – grams (g)– Weight – Newtons (N)– Liquid volume – liters (L)– Density – grams per cubic centimeter (g/cm3) or grams per milliliter (g/mL)– Time – seconds (s)– Temperature – Celsius (C) or Kelvin (K)

• Prefixes:– Kilo (K) – x1000– Centi (c) – x 0.01 or 1/100– Milli (m) – x 0.001 or 1/1000

See the “Metric Toolbox” or Page 15 of your textbook for more

Factor Label Method

1.Write what you know on the left2.Write what you want on the right3.Put a conversion factor in the middle4.Cancel units on top and bottom5.Multiply top and divide bottom (Or – move decimal to right if on top move decimal to left if on bottom )

Let’s Do an Example!• How many cm are in 2.75 m?

Do These On Your Own:• How many cm in 2.4 m?

• How many mg in 65.5 cg?

The Ladder Strategy• You can also convert between units by moving

the decimal point.• Warning! This will work when you are

converting between two of the same measurements but not when you are converting between two different measurements!

Let’s Practice!

Measuring Distance• SI unit of length is the meter

A meter stick is 1 m long. The numbered lines are cm; the very small lines

are mm.

cm

mm

Measuring Mass• Digital balances will be used to measure mass.

• It will be in either grams or kilograms.

Measuring Volume• Beakers, flasks, and graduated cylinders are

marked in mL.

• Measure from the bottom upward and estimate when necessary.

Lab Safety Concerns• Walk carefully around the room• Handle all equipment with care• Patiently wait your turn at stations• If lab equipment breaks – notify Mrs.

Liberatore immediately! DO NOT TOUCH BROKEN EQUIPMENT.

• Meter sticks ≠ Swords, Light Sabers, etc….