Science 7 – LT Unit 3
- Classification and
Introduce
Microscopes
Update Project Boards
 What do we know now?
 What have we been learning?
Big Picture – Where we
are heading
 Learn how to:
 Classify Organisms
 Use Microscopes
 Bring it together using critters and water
samples from our classroom pond
Classification
 A system to sort out organisms based on
their properties
 Scientific name is called TAXONOMY
(based on Greek word taxa = “to sort”)
 Observations used to determine
similarities and differences in organisms
Kingdom
Phylum
Class
Order
Family
Genus
Species
Kingdom – “King”
Phylum- “Phillip”
Class – “Came”
Order – “Over”
Family – “For”
Genus – “Great”
Species –
Spaghetti
Current System Used for
Living Things
 Carl Linnaeus 1700’s
 The species name is
sometimes called a
binomial (a two-term
name). For example, the
zoological name for the
human species is Homo
sapiens:
 In this case, Homo is the
generic name and refers to
the genus; it is capitalized;
sapiens indicates the
species: it is written in
lower case.
Keys
 Branching Key
 Dichotomous Key
Branching Key
 Asks Yes or no
Questions
 “Branches”
outward from
main question
 Ends when a
unique answer
is in place for
all items
Dichotomo
us Key
 “Di” – means 2
“It is either this
or that”
 Look at first
item
 Ask Question
#1 – move on
to question it
directs you to
Learning how to use the microscope
There are 2 kinds of microscopes:
Simple: one lens (magnifying glass)
Compound: 2 or more lenses
 Monocular – 1 eyepiece
 Binocular – 2 eyepieces
Parts of the Microscope
1.Revolving
Nosepiece
Holds the high and
low power objective
lenses; can be
rotated to change
magnification
Parts of the Microscope
2. Objective Lenses
Magnification
ranges from 4x to
40x
Parts of the Microscope
3. Stage
Supports the slide
being viewed
Parts of the Microscope
4. Diaphragm
Controls the amount
of light on a
specimen
Parts of the Microscope
5. Light source
Projects light
upwards through
the diaphragm,
the specimen, and
the lenses
Parts of the Microscope
6. Base
Supports the
microscope
Parts of the Microscope
7. Eyepiece lens
First lens you look
through.
10 x magnification
Parts of the Microscope
8. Arm
Used to support
the microscope
when carried
Parts of the Microscope
9. Stage Clips
Hold the slide in
place
Parts of the Microscope
10. Course
Adjustment Knob
Moves the stage
up and down for
focusing
Parts of the Microscope
11. Fine
Adjustment Knob
Moves the stage
slightly to sharpen
the image
Calculating Magnification
Multiply lens powers together!
What’s my power?
What are the powers of
magnification for each of
the objectives (letter C) we
have on our microscopes?
 Eyepiece: 10 X by itself
 Low Power: 4X
 Eyepiece x Lens = Total Power
 Power = 10 x 4 = 40
 mainly used for large objects/scanning
 Medium Power: 10 X
 Eyepiece x Lens = Total Power
 Power = 10 x 10 = 100
 High Power: 40 X
 Eyepiece x Lens = Total Power
 Power = 10 x 40 = 400
 mainly used for smaller objects/details
Safety Instructions
Make sure it is on LOW power
to start with! (smallest objective)
The stage should be all the way
down (you focus by slowly
moving it up!)
Don’t touch the lens of the
microscope with your hands!
Carrying the Microscope:
 Always hold in an
upright position
 Always use 2 hands!
 One holds the arm and
the other supports the
base.
 Never carry by the
eyepiece
Other Things to Consider:
 Never use the COURSE FOCUS
KNOB while on HIGH power.
 Why? You could break the lens!
$$$$$$
 only use the fine adjustment on high
power
TROUBLESHOOTING
What if you can’t get your object into focus?
 Check that you have one of the
lenses clicked into place
 Check that your disc diaphragm is in
place (not IN BETWEEN settings)
TROUBLESHOOTING
What if you can’t get your object into focus?
 Clean off your lenses using LENS PAPER.
(Not Kleenex tissue)
 GO BACK TO LOW POWER AND START
OVER!
Making a Wet Mount
 Put a drop or two of the liquid you are studying
on the slide.
 Place a coverslip on one edge of the drop.
 Slowly lower the coverslip onto the drop so that no
air bubbles get trapped under the coverslip.
Looks like a cool specimen
…but it’s not.
When putting the microscope away
(at the end of the class):
It should be on LOW power.
The cord should be WRAPPED around the
arm.
The stage should be all the way DOWN
(do this with the course focus knob!)
Put the dust cover back on
 Put carefully back on cart
 Check microscope into the teacher
Let’s Try it out!
In Journal: title “Microscope Drawing ”



Draw what you see after focusing the
image
Label the image (what is it called)
Label magnification (power) on drawing
For example:
Onion cell
Power = 10 x 40 = 400
Group roles:
1.
2.
3.
4.
Carefully go get a microscope
Get a slide on back table
Clear off desks completely
Clean up duty
Must pass microscope quiz
before you can do the Pond
Lab.