Transcript For Today… - Deer Valley Unified School District

Investigation 2:
Introduction to the
Microscope
At the end of
you will be able to:
• Identify and label the parts of the
microscope and describe their functions.
• Demonstrate proper care and procedures
pertaining to microscope use.
• Apply your knowledge of the focal plane
and field of view to observe and draw
microscopic specimens accurately.
Investigation 2 - Part 1
Meet the Microscope
The results of the investigation of the five
materials indicated that three of them were
alive- they were organisms.
Two of the organisms were so small that
they were difficult or impossible to see.
In order to take a closer look at the
organisms a special tool is needed- the
microscope.
• Carrying microscopes: www.fossweb.com
• Lab Notebook page 7: This short article has
lots of terms printed in bold text. As we read it
together, we will discuss the importance of the
bold and italic words and phrases.
• When we reach the end of the article, you
should label the parts of the microscope
diagram at the bottom of the page.
• You will be responsible for knowing the
information and following the rules in the article
when you use a microscope.
Microscope 411
Carrying:
• 2 hands
• One hand on arm
• One hand below
Enemies:
• Dust
• Water
Cleaning:
• Only use lens paper.
• NO tissue or paper towel
Using:
•Start with lowest objective lense (4x)
•Coarse adjustment brings stage close to the slide
•Check from the side- don’t look through eyepiece
yet
•LENS CAN’T touch the slide!!!!
•Only move knob to move lens away from the stage
Knobs:
•Use coarse adjustment when first examining
•Use fine adjustment lens to FOCUS (while looking
through eyepiece)
The Microscope Kits…
• Getters, please go get a microscope kit for
your group.
• Please listen carefully to the following
information…
PREPARING A DRY MOUNT
1. Place the material to be observed at the center
of a slide.
2. Place another slide on top of the material and
hold it flat.
3. Handle the dry mount by the edges only; place
it on the microscope stage.
4. Secure the slide by placing the stage clips on
top of the outer edges.
5. Use only the low (4x) and medium (10x)
objective lenses to view the dry mount.
WORK WITH YOUR PARTNER
• Prepare and observe dry mounts of the
letter e. Complete 1-3 on page 9 of your
lab notebook.
• What you see when you look through the
eyepiece of a microscope is called the
field of view. What shape is in the field of
view in your microscope?
Question to think about…
• What is the relationship between the
orientation of the object on the
stage and the appearance of the
image in the field of view?
The image is inverted (flipped top to
bottom) and reversed (flipped left to
right). www.fossweb.com
FEATHER AND PHOTO
OBSERVATIONS
• Complete parts 4 – 6 on
page 9
Investigation 2 - Part 2
Exploring the Microworld
THE LETTER e IMAGE
Yesterday, we looked at the microscopic
image of the letter e and discovered some
of the relationships between an object and
its image. However, we didn’t figure out
how big the e really is. It looks huge in the
microscope, but in reality it is quite small.
How can we figure out how big something
is by looking in the microscope?
Microscope challenge!
• Try to figure out what the
diameter of the 4x objective lens
field of view is using your
microscope kits!
• What is the distance between the
lines on the ruler?
• If you saw 5 lines, how long would
that be?
DISCUSSION QUESTIONS
What is the field of view in your
microscope when you are using the 4X
objective?
The field of view is about 4 mm under low power.
Can you estimate the diameter of the letter
e you observed yesterday?
The letter e was about 2 mm.
Questions to discuss…
What do you think will happen
to the field of view if you use
the 10x objective lens?
–It will become smaller.
MAGNIFY
The word magnify means to “make bigger.”
The numbers on microscope lenses tell you
how much they magnify the image of the object
you are looking at.
The eyepiece has 10x written on it. This means
it magnifies things ten times—things look 10
times bigger when viewed through the eyepiece
alone. The magnification of a lense is also
referred to as its power.
TOTAL MAGNIFICATION
The objective lenses have different
numbers on them. To determine the total
magnification of an objective lens and the
eyepiece working together, you multiply the
magnifications together.
For instance, when you use the 10x eyepiece
with the 4x objective lens, the product is 40,
so the object looks 10 times 4, or 40 times bigger.
MEASURE NETTING
• Take a piece of netting from the
microscope kit and put it on a piece of
white paper.
• Look closely at the netting. It is made of
little squares. How far is it across one of
the little squares?
– The squares are about 1mm or a little
more in width! Please record this in your
lab notebook on page 11.
PREPARING A WET MOUNT
1.
Place the object to be viewed on the slide.
2.
Add 2 or 3 drops of water.
3.
Place the ruler on top of the netting making sure the hatch marks
are in the center of the slide.
4.
Put a drop of water on the ruler.
5.
Take a clean coverslip, and drop gently onto the water droplets at a
45° angle.
6.
Use a small bit of soft paper towel (in kit) to blot up any excess
water.
LAB NOTEBOOK PAGE 11
• Complete the three parts on page 11 of
your Lab Notebook.
• Estimate the width of the netting squares
to the nearest 0.1mm.
• Draw exactly what you observe.
DISCUSSING MAGNIFICATION
• How big are the squares on the nylon
netting?
• About 1 mm
• What is the magnification when you use the
4x objective lens?
• 40X
• How wide is the 4x objective lens field of
view?
• About 4 mm.
DISCUSSING MAGNIFICATION
• What is the magnification when you use
the 10x objective lens?
• 100X
• What about the 10x objective lens field of
view?
• 1.8mm
DISCUSSING MAGNIFICATION
• What is the magnification when you use
the 40x objective lens?
• 400x
• What about the 40x objective lens field of
view?
• 0.4mm
DISCUSSING MAGNIFICATION
What is the relationship between
magnification and the diameter of the field
of view?
The greater the magnification, the smaller
the field of view.
We have been using the microscopes to
look at materials that are flat like paper and
netting. It is pretty easy to get these
materials in focus.
Sometimes, however, microscopes are used
to look at thicker materials. Let’s find out
what new factors come into play when we
use the microscope to focus in on three
dimensional materials.
RIBBON SLIDE PREPARATION
a. Select three different-colored samples
of ribbon. Carefully place them on top
of each other on the slide.
b. Wet the layers of ribbon with 3-4 drops
of water.
c. Place a cover slip on top of the
ribbons.
LAB NOTEBOOK PAGE 12
Please complete the tasks on this page.
FOCAL PLANE
• The lens system in a microscope is designed
to focus at one distance from the end of the
lens. If an object is not exactly at this distance,
it is out of focus. The distance at which a
microscope lens system focuses is called the
focal plane. Things that fall precise and
limited distance from the lens are in focus;
things above or below the focal plane are out
of focus.
Investigation 2 - Part 3
Microscopic Life
Getting Ready for Thursday
To prepare Brine Shrimp specimen:
• Measure ____ mL of fresh water, bring it back
to your table, and pour into your group’s vial.
• Return beaker to counter
• Measure _____ of salt, add to vial, stir
thoroughly until dissolved.
• Add 1 mini-spoon of eggs.
• Do NOT stir. Cap and return labeled vial to
counter. (Also return & clean [if necessary] any other materials)
Add this to a clean page in your SCIENCE notebook
Brine Shrimp: Characteristics of Life
yes
water
food
waste
response
reproduction
growth
gas exchange
no
BRINE SHRIMP
ARE THEY LIVING?
• Do the brine shrimp do all of the
things listed on the board?
• Can you observe them doing
these things?
• How could we observe them more
closely to get more evidence?
LAB NOTEBOOK PAGE 13
Please review the instructions on page 13.
Getters, please get microscopes,
microscope kits, vial holders and small
Flashlights.
The yeast you will put in with your brine
shrimp has been mixed with a red dye
called Congo red. It stains the yeast red
so it will be easier to see.
Put one small drop on the slide with the
brine shrimp. Observe the interaction at
40X and then 100X.
Page 13
1. Observe the brine shrimp using
the flashlight.
2. Prepare the brine shrimp wet
mount.
3. Observe
4. Add 1 drop of yeast
5. Observe
• How did the brine shrimp and yeast
interact?
• Is the feeding behavior evidence of
life?
• What did the shrimp do when you
shined the light on them?
• Did you see any other evidence of life?