Working as a scientist• Identify common lab equipment• Hypothesising, observing, inferring and concluding• Using thermometers• Format for report writing• Measuring mass and volume• Fair testing (controls and variables)
Hypothesising, observing, inferring & concluding• Observing – things or events that you notice. Eg. footprint, smell of perfume, sound• You infer something when you use your observation AND previous knowledge to explain something• Hypothesis – educated guess• Conclusion – final outcome of an investigation
Using thermometers• A thermometer is used to measure temperature in degrees Celsius (˚C)• When reading a thermometer you must have your eyes level with the top of the of the column (of mercury or alcohol).
Format for report writing• Aim: A short statement about what you are trying to find out. Must start with the word TO. Eg. To determine the battery brand which will last the longest in a clock radio.• Hypothesis: Your best educated guess of what you think you will discover. DO NOT USE THE WORDS ‘I THINK’ OR ‘I RECKON’. Eg. Duracell batteries will last the longest in a clock radio.
• Materials: A list of all the equipment/chemicals to be used. (This is sometimes called apparatus).• Method: A set of steps outlining how to do the experiment. Eg. 1. Pour 100ml of water into a 250ml beaker 2. …..• Results and observations: a presentation of your data – this usually includes a table and a graph.• Discussion: An explanation of your results.• Conclusion: A brief account of what you found out. Your conclusion should answer your aim. Eg. Everlast batteries lasted the longest in a clock radio.
Measuring mass and volume• Mass = how much matter there is an object or substance. The standard unit of mass is the kilogram (kg).• We use a triple balance beam to measure mass.
Measuring mass and volume• Volume is a measure of the amount of space that an object or substance occupies. The standard unit of volume for liquids is the litre (L).• To measure volume we use calibrated glassware (measuring cylinder, pipette).
Fair testing (controls and variables)• In a fair test all conditions (variables) except the one being tested should be the same.• Independent variable: The ONE thing you change• Dependent variable: The thing you measure (eg height, weight, time)• Controlled variables: everything else that must remain constant.
Key terms• Solution: a mixture of one substance dissolved in another.• Solvent: The substances in which a chemical can dissolve (usually the liquid).• Solute: The substance that dissolves (usually the solid).FOR YOU TO DO:• What is the solute and solvent in the following: milo, cup of coffee, swimming pool water, sea water?
Key terms• Soluble: substances which dissolve in a liquid.• Insoluble: substances which do not dissolve in a solvent.• Concentrated: more solute is dissolved in the solvent.• Dilute: less solute is dissolved in the solvent.THINK OF CORDIAL: The more cordial you add,the more concentrated your drink is!
Key terms• Saturated: When no more solute can be dissolved in a liquid. Think of your clothes being saturated – you cant get any more wet!• Sediment: particles that do not mix and settle to the bottom (like sand in water)• Suspension: when the insoluble substance is dispersed (spread) throughout the liquid, making it cloudy
Separation techniques• Evaporation: when one substance is heated and evaporates. Salt and water.• Crystallisation: separating sugar from water.• Filtration: uses filter paper to separate insoluble substances from soluble substances.
Separation techniques• Distillation: Separates based on differing boiling points.
Separation techniques• Decanting: Separates a liquid and a sediment – by allowing the sediment to settle to the bottom of the container and the liquid is poured off the top.
Separation techniques• Centrifuging: Spinning a mixture quickly – forcing the heavier substances to the sides. (eg washing machine)• Separating funnel: an apparatus used to separate 2 liquids that do not mix (eg oil and water)
Separation techniques• Chromatography: paints, inks and dyes are often mixtures of substances that have different colours – separating these colours out is chromatography.
Cells• Microscopes (light and electron, monocular and stereo)• Parts of a microscope• How to use a microscope• Calculating total magnification• Rules for sketching specimens• Staining specimens• Cells: look at plant and animal cells• Basic organelles: cell wall, cell membrane, nucleus, vacuole, chloroplast, mitochondria, cytoplasm• Unicellular vs multicellular organisms
Microscopes• Light microscope: uses light rays to see an image.• Electron microscope: uses electrons to see an image. We use light microscopes at school!• Monocular microscope: you use only one eye.• Stereo microscope: you use both eyes.
Calculating total magnification• To calculate the total magnification, you must multiply the magnification of your eyepiece lens and the objective lens. Eyepiece lens Objective lens Magnification 5x 5x 25 x 5x 10 x 10 x 100 x 40 x 400 x
Rules for sketching• Use a sharp pencil• Draw only the lines you see• Your diagram should take up about a third of the page• Record the total magnification• State the name of the specimen and the date observed• Label what you can
Staining specimens• Many specimens are colourless when viewed down a microscope, so specimens are often stained (or coloured) to make them easier to see.
Cells – plant and animal• All living things are made of cells.• The tiny ‘organs’ of a cell are called the organelles.• Plant cells have different organelles to animals cells.
Cell organelles• Nucleus: control centre of cell• Cell membrane: controls what goes into and comes out of cell.• Cytoplasm: where chemical reactions take place.• Cell wall: protection, support and shape.• Mitochondria: supplies energy.• Chloroplasts: photosynthesis.• Vacuole: large cavity (hole) storing water and other substances.
Unicellular vs multicellular• Some organisms are made up of a single cell – they are described as unicellular.• Multicellular organisms are made up of many cells with different types of cells doing different jobs.• What are some of the cells making up humans?
Solids, liquids and gases• What is matter/states of matter• What is volume, how can we measure volume• Particle model• Changing states: melting, freezing, evaporation/ boiling, condensation, sublimation,• Water cycle: cloud and fog• Convection, conduction, radiation
What is matter/states of matter• Matter is anything with mass and volume.• Matter can exist in 3 states: solid, liquid and gas.• Water is a liquid. What is the name of the solid and gas forms of water?
States of matter • The different states of matter have different properties.Substance State Can the shape Does it take up Can it be changed easily? space? compressed?Ice SolidWater LiquidAir Gas
Volume• The amount of space taken up by a solid, liquid or gas is called its volume.• The volume of liquids is measured in litres or millilitres.• The volume of solids are measured in cubic metres or cubic centimetres.• How can you measure the volume of an irregular shaped rock?
Particle modelThere are 4 parts to the particle model:• All substances are made of tiny particles• The particles are attracted towards each other and surrounding particles• The particles are always moving or vibrating.• The hotter the substance is, the more energy the particles contain and the faster they move!
Classification• Living, nonliving, dead• Dichotomous keys• 5 vertebrate groups
Classification• Classify means to sort into groups.• Taxonomy is the science of classifying organisms.• One feature that can be used in forming groups is whether something is living, non living (was never alive) or dead.• Sort the following: sun, leaf, bird, rose, water, wooden table.
Dichotomous keys• There are only 2 choices at each branch.
Vertebrate groups• Vertebrates: animals which have internal skeletons or backbones.• Invertebrates: animals which have an external skeleton or no skeleton.• 5 vertebrate groups: mammals, aves, reptiles, amphibia, fish.
Forces• Speed• Types of forces: gravity, magnetic, electrostatic• Contact and non-contact forces, buoyancy, friction
Speed• Speed is a measure of how quickly distance is covered.• Speed: distance time• Units: km/hr, m/sec, cm/min…..
Types of forces• Contact forces: require contact (eg friction)• Non-contact forces: no contact is required between objects (eg magnetism)• Gravity: pull towards Earth• Buoyancy: upwards push of object while it is floating• Friction: force applied to the surface of an object when it moves against the surface of another object
The Earth and Our Solar System• Earths structure• Importance of gases in atmosphere (greenhouse and ozone gases)• Night and day, seasons• Major features of universe (galaxies, stars, nebulae, solar systems)