LEEF Training event: Using microscopes with children and young people

USING MICROSCOPES WITH CHILDREN AND YOUNG PEOPLE

Wednesday 23 November 2015, 9.30am-3.45pmSouth London Botanical Institute SE24 9AQ

Programme:9.30-10 Arrive and coffee10-10.15 Introduction to the day 10.15-11 SLBI Garden in Focus — hands-on session exploring opportunities for microscope work in the KS1/2 science curriculum 11-11.15 Tea/coffee break11.15-12.15 ‘Interpreting the image: Arts/Science Projects using microscopes at Roots and Shoots’ -Dr David Perkins, Environmental and Educational Resources Manager at Roots and Shoots. David will examine what we can learn from watching live micro-organisms (e.g. in pond water) about life on earth - ecology, evolution, relationships. 12.15-1.15 Lunch and an opportunity for a private viewing of the art exhibition ‘The Fox Got you’, a photographic installation celebrating six common plants which are the origin of five major medicinal drugs.1.15-2.15 The wonderful world of microscopes: using them in environmental education with children and adults— Dr June Chatfield, well-known naturalist, Vice President of the British Naturalist Association, Fellow of SLBI and former lecturer in Environmental Science. June has promised some technical detail about magnification levels and light sources plus a look at mosses and lichens and some refrigerated leaf litter invertebrates.2.15-3.15 ‘Stepping Inside the cell-Microscopy for Primary School Children’ — Dr Claire Wells, Senior Lecturer in the Dept of Cancer Cell Biology and Imaging at Kings College London and Royal Microscopical Society committee member. Claire will be talking about an outreach project she ran for KS2 children and we will all get a chance to familiarise ourselves with the processes of making slides and images under her expert tuition.3.15-3.45 Tea, cake and feedback

LEEF Training event: Using microscopes with children and young people

Microscopes: Some definitions of termsOptical microscope—a microscope that uses visible light to make an image. The light is refracted with optical lenses to create the image.

Compound microscope—a microscope with two lens systems: the objective and the eyepiece or ocular lens. Both eyepiece and objective lens may be replaced or rotated to give a range of possible magnifications and resolutions. Compound microscopes may be monocular or binocular but both eyes share the same view producing a 2D image.

Stereo microscope—a microscope with two eyepieces whereby each eye sees a slightly different image to create a stereo or 3D view (relies on the principle of Victorian stereoscopes to create a 3D picture). Stereo microscopes are always binocular.

Binocular—a microscope with two viewing tubes. May be more comfortable if using all day every day. Adjustable but be aware that may not be sufficiently adjustable to fit very small faces of young children.

Monocular— a microscope with a single viewing tube.

Objective—the lens at the end of the microscope view immediately above the specimen.

Ocular lens (eyepiece)—the lens that the viewer looks through.

Total magnification—the sum of eyepiece x objective magnification, see also resolution below.

Resolution—this terms refers to the amount of detail that will be captured and relayed to the eyepiece i.e. the ability to show fine detail in the image. The resolution of a microscope image depends on the objective lens: the eyepiece lens can magnify that image and make it bigger but not more detailed. Thus a microscope with 40x magnification on the objective lens and 10x on the eyepiece will create a higher resolution (sharper detail) image than a model with 20x magnification on the objective and 20x on the eyepiece lenses although total magnification will be x400 in both cases.

Field of view or depth of field—the diameter of the circle of light that you see when looking into a microscope. As the power gets greater, the field of view gets smaller i.e. field of view is less at higher magnifications. There is less need to move the slide/specimen about when working with a wider field of view (because you can see more of it).

Coarse focus—the rough focus knob which adjusts the distance from the objective to the specimen and so moves the subject quickly through the focal plane. Many less complex microscopes only have a coarse focus function.

Fine focus— the knob used to fine tune the focus on the specimen, normally one uses the coarse focus first to get close then moves to the fine focus knob for fine tuning.

LEEF Training event: Using microscopes with children and young people

Achromatic lens—a lens which has been corrected so all chromatic (colour) and spherical (focus or flatness of field) aberrations are restricted to the outer edges of the field of view (normally the outer 40%, higher quality lenses that restrict aberrations to the outer 20% or are even 100% corrected are available but are very much more expensive).

DIN standards—Deutsche Industrie Norm i.e. German standard for the manufacturing of microscope lenses which has been adopted internationally (and replaced earlier standards such as the RMS standard). DIN lenses aren't necessarily better than non-DIN but they will be interchangeable from one DIN microscope to another. JIS is the Japanese equivalent standard. Note that there is no equivalence between these three standards.

Questions to consider when purchasing a microscopeWhat will you use it for most frequently? (3D opaque objects or 2D transparent ones?)

Who will us it most frequently and what level of expertise will they have? (What age? If you envisage using microscopes mainly to cover cell biology components of KS3/4 science curriculum you might choose very different model to someone working mainly looking at pond and leaf litter invertebrates with primary school age children.)

Where will they use it? (In the field? In a multi-purpose space? At a dedicated microscope station? Does it need to be cordless? Implications for light source.)

How robust should it be? (Age of users, portability etc)

What magnification is appropriate? (How deep into the cell do you want to go?) And at what resolution?

How precise/fiddley do you want the focusing to be?

How tricky do you want sample preparation to be? (slides, sections, staining etc)

How long will people be using the microscope for in any one session? (Comfort of user: angled eyepiece/s rather than straight above and binocular? But also light source may need to be a ‘cool’ light source e.g. LED to avoid frying specimens.)

What’s your budget?/Are there any grants available?

Do you want to be able to purchase additional eyepieces/objectives to increase the range of use to which you can put the microscope? (If so, you will need a microscope which is modular construction and meets DIN standards.)

Do you want to attach a camera/video camera/be able to show the images on computer screen?

LEEF Training event: Using microscopes with children and young people

Specific considerations when using microscopes with children Monocular or binocular: mono might be advantageous for the very young who may not be able to

adjust two eyepieces close enough together for satisfactory use. Robustness and stability may be of increased importance: less stable microscopes are more prone

to picking up vibrations and transferring these to the image which can make it fuzzy and less satisfying.

Relationship of the image to the specimen (children esp. younger children e.g. KS1/2 will find it easier to relate to a crisp clear, upright image which can be related to the item they are viewing without too much interpretation. Counter-intuitively, lower magnification e.g. 10x or 20x may be better because it facilitates this connection: seeing a detailed image while being able to handle the specimen can be a very convincing learning tool).

How simple do the controls need to be (one knob to focus and single objective with limited risk of sending objective crashing down into the sample; ability to control lightsource—thankfully old style fiddley microscopes that some of us might be old enough to recognise from our childhood with a rotatable mirror under the viewing stage have been supplanted by electric lighting with most student models using LEDs, but some still rely on a natural light source; field of view—how much of the specimen do they need to be able to view without needing to move it once all set up and in focus? Etc) Note that models with a fine focus function may be trickier to focus but can provide a clearer image which is more relatable for younger children.

Will children be sufficiently old/experienced to prepare slides (scalpels, glass slides, chemical stain) or will it be more useful to have a microscope able to view 3D objects such as dead bugs or seedheads which can be popped under as they are or mounted simply on card?

Is a microscope the most appropriate way of magnifying something for very young children? Simple magnifying glasses or cheap handlenses may achieve the desired goal more simply.

LEEF Training event: Using microscopes with children and young people

Comparative features of different kinds of entry-level microscopesSome considerations apply regardless of the type of microscope selected. For example, metal microscopes are more durable and provide greater stability than plastic; better quality optics provide better quality images (glass not plastic)

Type of microscope Main features Advantages Disadvantages Guideline price Child-friendliness‘Toy’ microscopes available from department stores and educational toy stores

Often claim high linear magnification e.g. 500x or even 1000x.Brightly coloured plastic body with plastic lenses.

Light and portable; bright colours attract very young children.

Insufficient resolution to view images at the stated magnification (need careful sample prep, good optics and specialised lighting to get good results at such high magnification): produce poor quality fuzzy images.Not very stable: vibrations make poor quality image even more blurry.Poor quality plastic lenses are not corrected for lens errors.

£25-50ish Poor: frustrations involved in using these toys can put children off rather than encouraging them into the wonderful world of microscopy.

Introductory monocular microscopes e.g. Motic MS2

Relatively low magnification.Monocular.Upright image.Large simple controls.Removable base plate.No sample preparation

Generally metal and better quality than toy microscopes mentioned above.Easy to relate image to specimen viewed. Single magnification (usually

Coarse focusing only.Monocular may not be comfortable for prolonged viewing (although binocular may not be suitable for younger children in any

£60ish (and RMS grant may be available)

A good general introduction to microscopes for children and adult beginners.

LEEF Training event: Using microscopes with children and young people

necessary. 20x) enough to see detail not apparent to naked eye but not so much as to make it unrecognisable.Single eyepiece may be easier for young children.No sample preparation required: pop it under and go.

case).Single magnification only (usually 20x).Tend to rely on natural light which can be tricky in some contexts.

Stereo microscopes Binocular with each eyepiece giving slightly different view to create 3D image.Upright image.Low magnification (5x-40x)Good depth of field.More complex models have interchangeable objectives with different magnifications.Focusing knob plus height adjustment on stand for larger or smaller objects.Built in lighting at top and base (depending on model).

Wide field 3D image the right way up is easy to relate to the specimen under view.Good for opaque 3D subjects.No sample prep required.

Binocular eyepieces may be insufficiently adjustable for young children.More complex to use especially if interchangeable objectives.Height adjustment risks objective lens toppling on to specimen to detriment of both.

£75 upwards depending on versatility of the model selected.

Easy to relate image to object and able to look at whole range of common 3D objects without needing to prepare the specimen or fiddle with artificial light sources. Low magnification means less abstraction from the real world.Binocular may be confusing.More versatile models are significantly more complex to use.

LEEF Training event: Using microscopes with children and young people

Compound microscopes Light is shone through subject so prepared thin specimens are needed. Higher magnifications are possible (e.g. 50x-400x)Image is inverted.Shallow depth of field.Binocular or monocular (but each eye sees same image).Modular construction means range of eyepieces and objectives can be used to give range of magnifications and resolutions.Fine and coarse focusing

Able to see cellular structure of plant and animal specimens.Wide variety of pre-prepared slides are available.

Sample preparation is required. Harder to relate higher magnification inverted image to the object under view: may require interpretation.Complex focusing. External lighting is required.

£60-180ish Inverted image makes orientation confusing.Complex to use requiring more time for instruction.Lower depth of field makes it trickier to ‘find’ the specimen.The only type of microscopes capable of looking at e.g. the nuclei of cells or bacteria.

LEEF Training event: Using microscopes with children and young people

Recording imagesMicroscope images, moving as well as still, can be recorded very simply using a compact digital camera, a webcam or even a mobile phone. These devices can be regarded as ‘electronic eyeballs’, and so are capable of picking up an image when placed at the eyepiece of a microscope. A couple of simple conditions apply. First, the height of the camera lens above the eyepiece must be arranged so that the full field of view of the eyepiece can be seen. Look for the ‘exit pupil’ of the microscope – the small patch of light that comes to a focus 10–15 mm above the top of the eyepiece and which can be seen by holding a piece of thin paper above the eyepiece. The exit pupil normally falls on the pupil of the eye, and similarly needs to enter the camera lens if the whole field of the eyepiece is to be seen. Some cameras with large and complex lens systems and some eyepieces with a low exit pupil will not be suitable; in general, the smaller and simpler the camera the better. Ideally, some system of supporting the camera in the correct position should be devised. At its simplest, this could take the form of a piece of thick wood with a hole to accommodate the eyepiece tube, forming a platform for the camera to rest on. The hole can be lined with strips of the soft half of self-adhesive Velcro to provide a friction fit. Second, since our eyes are generally focused on infinity when looking through a microscope, where possible the camera autofocus should be disabled and focus set on infinity. The flash, if any, should be disabled.

With thanks to Peter Evennett for the information in this section which is taken from his article: Smaller than we normally see: the fascination of microscopy is not restricted to biology SSR March 2011, 92(340).

Further detailed advice on attaching a camera to a microscope can be found at:http://www.microbehunter.com/connecting-a-camera-to-a-microscope/

Additional notes from the dayExcellent resources provided by Science and Plants for Schools (www.saps.org.uk) based at Cambridge Botanic Garden.Complete book of the Microscope by Bines et al. 2012 (Usbourne Internet-linked Reference Books) is a good practical guide for beginners and includes information on commonly available stains etc.Great idea to get kS1/KS2 pupils really looking at plants: create a name for a given tree/plant specimen based on the observable characteristics of that plant e.g. the spiky, hairy, fairy forest tree.

Dr David PerkinsUsing microscopes to view life in ponds/puddles/pools of water collected from under water fountains etc is a great way to demonstrate the tenacity of life.

LEEF Training event: Using microscopes with children and young people

Start off with a general introduction to lenses: glasses and eyes, get pupils to experiment with focal length by bringing their finger tips towards their noses: too far away and finger is not clear ditto too close, somewhere en route is just right.Use a 50cm ruler or informal scale to demonstrate magnification i.e. this millimetre will be represented by 4cm if magnified 40x; 40cm if magnified 400x etc.Great advantage of monocular microscopes is to allow children to draw what they see simultaneously with viewing it. Or if projecting the image on a large screen get them to draw in the dark to emphasise the connection of brain, eye and hand.Circular paper: draw what you see in the microscope view.Microscopic water creatures can be observed to exhibit all the characteristics of living things under the lens: they feed, excrete, reproduce (visible egg sacs), panic, sense one another and take evasive action etc. Great route in to discuss the characteristics of living things and the importance of animal welfare and concern for creatures less than 1mm long.Ideally have a photo /model of some of the creatures you are likely to find in pond water to be able to point to specific features as you view them under the lens. This helps in the relatability of image to specimen for younger pupils.Diatoms: plants with silicaceous structure ‘plants with a glass skeleton’.Ideas for extension work: “Poetry in a puddle” and spiral snail shell poems.Small Freshwater Creatures by Olsen et al. 2001 (Natural History Pocket Guides) OUP is a good clear guide to commonly occurring pondwater creatures.Useful resources and guidance available at www.microscopy-uk.org

Dr June ChatfieldMicroscopes, hand lenses and magnifying glasses are all about understanding and manipulating light.Higher magnification is not necessarily better: depends on what you are trying to see.Lower power spreads the available light; higher power concentrates the light. Higher magnification microscopes may have a condenser to assist with the concentration of the available light.To pick up the texture of a 3D specimen e.g. seed cases, use a low angle light source rather than incident lighting from above.Translucent specimens e.g. pond plants such as Elodea or mosses (1cell thick) benefit from being bottom lit i.e. transmitted light under the microscope stage.Colourless plant and animal tissues will require a stain: commercially available prepared slides will use histochemical tests to colour different parts of the preparation different colours (because different chemicals take up and react with the different chemicals present in the specimen e.g. lignin)As a general rule, liverwort leaves don’t have a midrib but mosses do because they live in drier places so need the extra rigidity provided by midrib structure (link to habitats and adaptation).

Dr Claire WellsEmphasised that few primary school teachers are science graduates: this is one place where environmental educators can add value.If purchasing digital microscopes e.g. Digi blue, beware that software upgrades can render equipment obsolete.4 week project, 2 hours per week, ‘Stepping inside the cell’. Week 1 Elodea (no stain necessary), Week 2 onion skin (iodine stain, applied by adult supervisors, children in lab coats and goggles to comply with school H&S concerns), Week 3 cheek cells (again, stain necessary and applied by adult supervisors).Slides and cover slips set out ready. Children shown how to label upper side of slide and carry safely in first session.

LEEF Training event: Using microscopes with children and young people

Target outcomes for project: pupils to understand what a cell is, main features of cell, key differences plant and animal cells.