# Document

```How do you compare very
small numbers?
Size of a period: 0.0006 m
Size of a bacteria cell:0.0000021 m
In this lesson you will learn
how to make rough
comparisons of very small
numbers by using scientific
notation.
Let’sReview
Review
Let’s
Writing a small number in scientific notation.
0.00000032
−7
A Common
Let’s
Review Mistake
Which is larger?
−5
0.00002
−6
0.000008
2 &times; 10
8 &times; 10
Core
Lesson
Let’s
Review
What’s the missing exponent?
3
?5
8
10 &times; 10 = 10
−8
?2
−6
10 &times; 10 = 10
Core
Lesson
Let’s
Review
Size of a period: 0.0006 m
Size of a bacteria cell:0.0000021 m
About how many times greater is the
period?
−4
Period: 6 &times; 10
3 times 100
Bacteria: 2 &times; 10
times greater
In this lesson you have
learned how to make rough
comparisons of very small
numbers by using scientific
notation.
Guided
Practice
Let’s
Review
A certain white blood cell is about
0.0000021 m long. A certain red blood
how much larger is the red blood cell?
Extension
Let’s
Review Activities
Research computing speeds of computers
from two different decades. How long did
it take the older computer to perform an
much faster is the newer one?
Extension
Let’s
Review Activities
Research and compare masses of various
elements from the periodic table.
Quick Quiz
Let’s
Review
A cell membrane is about 0.000005
mm thick. A certain virus is about
0.00009 mm across. How much
larger is the virus compared to the
thickness of the cell membrane?
A human hair is about 0.00012 meters
wide. A red ant is about 0.005 meters
long. About how much larger is the ant’s
length than the hair’s width?
```