Approximately
how many cells
in the human
body?
10 Trillion
Approximately how
many bacterium in a
human body’s biome?
100 Trillion
Metric
Measurement
Review
Metric Prefixes: kilo- to mili-
Metric Prefixes
 mL  Liter
 mL are a small unit—how many drops per mL
 Liters are a larger unit
 Bigger unit of measurement= bigger or smaller number?
 Move decimal to the?
7000 mL
Using Graduated Cylinders-Volume
 Value of graduation marks (lines)
 Distance between long lines
 Count lines & do simple math
40-20= 20 mL between
long lines
10 lines between long
lines
20/10= 2 mL per line
Using Graduated Cylinders-Volume
 Value of graduation marks (lines) ?
 Reading a graduated cylinder
 Meniscus – The curve of the water
 Read at the BOTTOM of the curve
 Example=?
Using Graduated Cylinders-Volume
 Take measurement as precise as
equipment allows
 Estimate to the next place
 Example=?
 Volume of object= difference of first
measurement and second
 Ex 70.5 & 75.0= difference/volume of ?
Volume through dimensions & equation
 Volume= Length x Width x Height
 Thickness of slide 1mm =
cm3
 Human error

Measurements

Calculations
 More accurate when there are less steps required because there is less
human error
 Always use equipment that allows you to get the answer you want if possible
Graduated Cylinder for Volume instead of Ruler
Volume by Formula
 Item too large to use graduated cylinder?
 Length x Width x Height
 Aquarium
 cm3=mL
 mLL
Divide by 1,000 or move decimal to the left 3 places
 Lgallons
 Appropriate measurements
 Inside dimensions
TRIPLE BEAM BALANCE
• Zeroing balance BEFORE measurement
• Pointer
• Zero Mark
• Adjustment Knob
Triple Beam Balance
 LargestMediumSmall
 Add values of three arms to get total Example?
 Estimate one place further
Comparing Balances
 Triple Beam Balance
 Electronic Balance
 Zero
 Zero
 More precise
measurement
 Less precise
135.15
 More human error
135.0
 Less Human Error
Precision of Measurement
 100 grams vs. 100.0 grams
 100 grams = 99.5-100.4 grams
 100.0 grams= 100.0-100.04
 Always measure as accurately as possible with
equipment
 Estimate one place further
 Don’t give answers of around 2 when it is 2.33333
Percent Error
 The difference in the accepted value and your value
 Divide by accepted value
 Multiplied by 100
 Your answer 10.5
10.5-10= .5
Accepted value 10
.5/10=.05
.05 x 100= 5.0%
Color Challenge & Density
 Directions should have left you with rainbow with 10mL in each test tube
 Left over water in tubes
 Inaccurate measurements
 Mass & Volume  Density
 Mass/Volume=Density g/cm3
 Ruler Errors
Element Flashcards Set 1
1.
Hydrogen
2.
Nitrogen
3.
Neon
4.
Carbon
5.
Helium
6.
Oxygen
7.
Fluorine
8.
Beryllium
9.
Boron
10. Lithium
O
 Turn Over 
Oxygen