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: human  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) 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!) 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! 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. It should be on LOW power. The cord should be WRAPPED around the arm. The cord should be WRAPPED around the arm. The stage should be all the way DOWN (do this with the course focus knob!) The stage should be all the way DOWN (do this with the course focus knob!) Put the dust cover back on 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.Carefully go get a microscope 2.Get a slide on back table 3.Clear off desks completely 4.Clean up duty

Must pass microscope quiz before you can do the Pond Lab.