Slide Preparation L/O - To be able to prepare a microscope slide D. Crowley, 2007

Microscope Crossword Have a go at the microscope crossword - you have five minutes… Down: - Lens that you look down What the slide is placed on A wheel to make the image clear Across: - Lens closest to the slide The specimen is placed on this You need this to see something Eyepiece Stage Focusing Objective Slide Light

Microscopes Set up a microscope to view an animal cell - remember the steps to take Place the smallest objective lens (the smallest lens) over the hole in the stage Turn the coarse focusing wheel to make the gap between the stage and the objective lens as small as possible Place a slide on the stage, and secure with the clips Adjust the light source so light goes up through the stage Turn the coarse focusing wheel slowing, until your specimen is in focus To see your specimen in more detail, turn the next largest objective lens over your specimen Use the fine focusing wheel to get your image into focus again - do not use the coarse focusing wheel - this can break your slide!

Preparing Specimens A specimen is the object we look at under a microscope The specimen needs to be thin, so light can pass through it We use a coverslip between the slide and specimen which helps flatten it out. It also helps keep the specimen in place, and stops it drying out When you have prepared your specimen you can look at it under the microscope. It is vital you know what magnification you are using: this is easy to work out - it is the eyepiece lens x the objective lens: Magnification = magnification eyepiece lens x magnification objective lens

Place your onion skin onto the water droplet on your slide Preparing Onions You are going to prepare a slide containing a specimen of onion cells Follow the slide preparation steps, then draw what you see (using A4 plain paper and in pencil). Also write down your magnification Magnification = magnification eyepiece lens x magnification objective lens Place a drop of water on the centre of a slide (this may contain a stain to make the specimen more clear, e.g. iodine) Cut some onion, then using forceps, peel off the inside layer of a piece of onion Using a mounted needle, lower a coverslip onto the onion skin. Do this slowly and carefully, to avoid trapping air bubbles! Place your onion skin onto the water droplet on your slide

Magnification When you have prepared your specimen you can look at it under the microscope. It is vital you know what magnification you are using: this is easy to work out - it is the eyepiece lens x the objective lens: Magnification = magnification eyepiece lens x magnification objective lens E.g. eyepiece lens = 10x objective lens = 60x Magnification = 10 x 60 = 600x magnification

Marking your drawings Level 3 Level 4 Level 5 Prepare a slide with help Focus the image with help Indentify parts of the microscope Draw what they can see Identify parts of cell with help Level 4 Identify most parts of microscope and state their job Draw simple diagram of cell seen under microscope Identify nucleus and cell wall Level 5 Prepare slide safely, with only a little help Focus microscope with only a little help Name most parts of microscope and describe how they work Draw an accurate diagram of cells under the microscope Identify and label parts of cell correctly

Marking your drawings Level 5 Level 6 Level 7 Prepare slide safely, with only a little help Focus microscope with only a little help Name most parts of microscope and describe how they work Draw an accurate diagram of cells under the microscope Identify and label parts of cell correctly Level 6 Prepare a slide safely without help Focus the image at low and high magnification Identify all parts of microscope and describe how they work Draw an accurate diagram of cell seen under microscope Make a reasonable estimate of the size of the cell Level 7 Prepare a slide safely and competently without help Focus the image at all 3 magnifications Explain in detail how the microscope works Identify and label parts of cell correctly, identifying problems Make a accurate measurement of the size of the cell