6th Grade Science Units
1. What is Science?
Scientists do a range of jobs, working together in communities to develop new knowledge.
CAS: A community of scientists works together discussing and developing ideas.
Assessment: crit F Rainbow; crit C Equipment; crit AB scientist article
What do scientists do? What features are there in the lab? What is the equipment called? How can we be safe in a lab? How do scientists measure? Who are scientists? What do scientists do?
Safety
Safety equipment around the lab includes the fume cupboard, fire extinguisher, gas cut-off switch, and safety screens.
Chemical containers are labelled with the name of the chemical and a hazard warning symbol.
Equipment
Apparatus used in science includes: test tube, beaker, measuring cylinder, tripod, gauze, Bunsen burner, conical flask, thermometer, clamp, retort stand, metre stick, balance.
Diagrams of apparatus show simplified 2D cross sections.
Measuring
Units are needed for each measurement: m, cm or mm for length, kg or g for mass, °C for temperature, and s for time.
Measuring cylinders (not beakers) are used to measure the volume of a liquid.
A balance is used to measure mass.
Scientists
Scientists work together on experiments or theoretical work.
Scientists use ‘the scientific method’ to find out new ideas about the world. They need to plan experiments,hypothesise, measure, observe, analyse, make conclusions evaluate, and communicate their work.
Scientists know much about the world, but there is much still to be found out. Scientists do not always agree about their theories, and many ideas in science are controversial, e.g. dark matter.
2. Plants for food(Potatoes)
Plants use photosynthesis to capture energy from sunlight and store this in organic molecules, which humans then use for food to give them energy and material for growth.
HI: Humans have developed techniques for maximizing yields from crop plants.
Assessment: crit E Scientific description of potato crop; crit AB Organic or artificial fertilizer
How does a plant grow? What is the structure and function of plants? How do humans use plants for food?
Cells
A cell is the unit from which biological organisms are built and carries out life processes: movement, respiration, sensitivity, growth, reproduction, excretion, nutrition.
All living organisms are classified into five kingdoms: plants, animals, fungi, bacteria, protista.
Classification
Bacteria and protoctists are made of a single cell (unicellular). Animals, plants and fungi are made of many cells (multicellular).
Plants are autotrophs- they make their own food in their leaves by photosynthesis. Animals are heterotrophs and must consume food.
Each living organism is part of a species. The binomial naming system for species is a latin name e.g. panther tigris.
Plants and photosynthesis
Plant organs include stem, fruit, flower, seed, roots, leaves. Each organ has a specific function which enables the plant to survive and reproduce.
Humans use different parts of plants for food. Artificial selection breeds plant varieties with characteristics useful to humans. All crops were originally wild plants.
Plants make food (carbohydrates) in their leaves by photosynthesis using carbon dioxide and water, producing glucose and oxygen.
The rate of photosynthesis depends on the temperature, availability of water and carbon dioxide and light levels.
Chlorophyll is the green chemical in leaves which enables the plant to photosynthesise.
A potato is a tuber, a food store for a plant to enable it survive the winter when light levels are low.
Fertilizers
Plants need minerals from the soil which are dissolved in the water they take up through their roots.
Artificial fertilizers replace the nutrients removed from the soil when a plant is grown. They usually contain nitrogen, phosphorous and/or potassium.
Organic fertilizers are made from manure or other organic waste and also contain a mix of soil nutrients.
Different species of plant are adapted to grow in different conditions (light levels, temperature, soil, etc.)
Data
Bar charts are used to represent discontinuous or grouped data.
Mass is measured in kilograms (and g, mg) using a balance.
Length is measured in metres (and km, cm, mm) using a ruler.
There is variation of characteristics of living things and this often follows a normal distribution.
3. Particle Theory
The particle theory of solids, liquids and gases explains many macroscopic properties of materials including flow, density and diffusion.
HI: Scientific models help to explain the macroscopic properties of materials.
Assessment: crit EF Heating Water; crit DE Paper towels; crit B Particles explanations
How can we explain the properties of solids, liquids and gases? What is everything made of? What happens during a change of state?
Using a Bunsen burner
A Bunsen burner should be set up with a heat proof mat, gauze, and tripod.
The safety flame is used when the Bunsen is on but not in use. For this the hole is closed.
The blue flame is used for gentle heating. For this the hole is half open.
The roaring flame is used for strong heating. The hole is completely open to allow oxygen in.
Physical properties of solids, liquids and gases
Solids are incompressible, have a fixed shape and a higher density.
Liquids are incompressible, have no fixed shape, can be poured and have a fairly high density.
Gases are compressible, have no fixed shape, can be poured and have a low density.
Solids can be stretched.
Liquids and gases can diffuse.
Particle theory
Particles are very small, and are not destroyed or made during physical changes. The particles could be atoms, molecules or ions.
The overall mass of particles stays the same when a change happens.
Particles in a solid are strongly held together and vibrate about fixed positions.
Particles in a liquid are more weakly held together and move around.
Particles in a gas move around quickly and randomly, occasionally colliding and bouncing off.
Particle theory can be used to explain expansion, diffusion, stretching and heat transfer.
Changes of State
A change of state takes in or gives out energy.
A solid changes to a liquid (and a liquid to a solid) at the melting point.
A liquid changes to a gas (and a gas to a liquid) at the boiling point.
Sublimation occurs in a few substances when they change directly between a solid and a gas.
The boiling point of water is 100°C and the melting point of ice is 0°C, at normal pressure.
As a solid is heated, its particles vibrate faster.
When a liquid or gas is heated, the particles move faster.
A higher temperature means faster particles with more energy.
At absolute zero (-273°C), the particles stop moving completely.
4. Investigating the Heart
The heart powers the circulatory system, pumping blood through the body to supply cells with food and oxygen and remove wastes. The circulatory system has two loops, so the heart is two pumps in one.
HSE: The heart is a vital organ for circulating the blood.
Assessment: crit DEF Heart rate investigation; crit C Heart unit test
What is the function of the heart and blood? What is the heart for? What affects the heart rate?
The heart is an organ which pumps blood around the body to transport food, oxygen, and wastes.
The heart is made of cardiac muscle and is controlled by the autonomic nervous system.
The heart has two sides- the right side pumps blood to the lungs to pick up oxygen; the left side pumps blood around the rest of the body.
The blood contains red blood cells, white blood cells, platelets and plasma.
Red blood cells carry oxygen.
White blood cells fight disease.
Platelets help the blood to clot.
Plasma is a liquid which carries dissolved food and other substances.
The heart rate is measured in beats per minute. A pulse can be felt where an artery is close to a bone near the skin.
During exercise, the muscles use more energy, so the heart must pump blood faster through the body.
Scientists design experiments which are ‘fair tests’. To focus their experiment on just one factor, they keep all other factors the same. These are called ‘control variables’.
5: Forces and Structures
Forces ideas determine the design of built structures.
ENV: The structure of buildings in the local environment can be understood with forces ideas.
Assessment: crit F bridges
How are forces ideas used to design structures?
Force
Forces are interactions between two objects. Some common forces include push, pull, gravitation, friction, air resistance, upthrust, thrust, magnetic and drag.
Forces are measure using a Newtonmeter in Newtons.
Force diagrams show forces using arrows. The length of the arrow shows the relative size of the force.
When forces on an object are balanced, it stays stationary or at the same velocity.
When forces on an object are unbalanced, it changes speed, direction or shape.
Forces can compress or stretch materials.
Materials
Some materials are strong under tension including rope and steel, while others are strong under compression including stone and concrete.
The greater the force, the greater the extension of a material under tension.
Structures
An arch transfers the weight (gravitational force) of materials to the base on each side.
Built structures use different materials for different parts of the structure depending on whether it is under tension or compression.
Arch bridges and flying buttresses use materials which are strong under compression.
Suspension bridges have parts which are strong under compression and tension.
A triangle is a stronger shape than a square because it transfers shear forces.
6. Exploring the Solar System
The Earth and other planets orbit the sun, the moon orbits the Earth, and the relative motions of sun, moon, Earth and planets give us our celestial view. Robotic missions have returned data on the moon and other planets.
ENV: exploring our distant environment
Assessment: crit AB Robotic space exploration presentation; crit E Position of sun in the sky measurements and explanation
What’s out there?
The solar system contains 8 major planets which orbit the sun.
The Earth orbits the Sun in one year giving seasons due to the angle of tilt.
The Earth rotates on its own axis in one day giving day and night.
The position of the Sun in the sky changes with the time of day and year.
The position of the stars in the sky changes over the night as the Earth rotates.
Space Exploration
People first tracked the sun, moon and stars with the naked eye.
The telescope allowed much more detailed observations to be made, including views of the planets as discs, which was strong evidence for the Sun being at the centre of the solar system.
The first rockets left the Earth’s atmosphere in the 1940s.
Space probes have explored the planets since the 1960s, to discover more about their origins, their moons, rocks, atmospheres and the presence of water.
Human missions to the moon and robotic missions to Mars have explored the surface of these objects
Earth and Sun
The Earth revolves on its axis once per day, and this causes day and night.
The Sun appears to move in an arc across the sky, rising in the east and setting in the west, due south at midday.
The length of shadows changes over the course of a day as the height of the sun above the horizon changes.
The point where the sun rises and sets changes over the course of a year.
The maximum height of the sun changes over the course of a year and depends on the latitude.
The length of the day changes over the year and is longest in midsummer (summer solstice), shortest in midwinter (winter solstice) and exactly 12 hours at spring and autumn equinox.
The Earth takes 365¼ days to orbit the Sun and the quarters are added as an extra day for leap years.
The seasons occur because the Earth is tilted on its axis and as it orbits the sun once a year, the northern or southern hemisphere is tilted towards the sun causing the sunto rise higher in the sky.
The moon orbits the Earth every 28days.
Stars
The stars, including the Sun, are luminous and made of hot gas.
Constellations are patterns of stars in similar directions in the sky which may or may not be close together in space.
The pattern of stars revolves around the pole star as the Earth revolves on its axis.
The visible constellations changes over the year and is different in northern and southern hemispheres.
The Solar System
The solar system consists of 8 major planets which orbit the sun in ellipses.
The 8 major planets are Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.
Jupiter and Saturn are gas giants and the rest are rocky planets
Planets closer to the sun tend to be warmer.
Planets differ in their gravitational field strength, atmosphere and composition.
Mars is a rocky planet made of volcanic deposits, with deposits of ice.
The atmosphere of Mars is much thinner than Earth’s and the average temperature much colder.
Mars has a similar day and seasons to Earth.
7. Water and solutions
Dirty water contains a mix of soluble and insoluble contaminants, and these can be removed by filtering and distillation.
CAS: purifying water
Assessment: crit AB Lifestraw; crit C unit test
How do we purify water?
Solutions
A solute dissolved in a solvent makes a solution.
Gases can also dissolve in liquids.
When a solid dissolves in a liquid, the particles are too small to see, but are still there, so mass is conserved.
Substances can be classified as soluble or insoluble.
The concentration of a solution is the number of grams of solute dissolved in 1 litre of solvent.
Solubility depends on temperature.
A saturated solution is one where the maximum possible solute has been dissolved.
Dirty water may have both soluble and insoluble contaminants.
Filtering separates insoluble substances from a liquid.
Evaporation and distillation can separate out a solution because different substances have different boiling points.
Properties of solids, liquids and gases
Solids are incompressible, have a fixed shape and a higher density.
Liquids are incompressible, have no fixed shape, can be poured and have a fairly high density.
Gases are compressible, have no fixed shape, can be poured and have a low density.
Particle theory
Particles in a solid are strongly held together and vibrate about fixed positions.
As a solid is heated, its particles vibrate faster.
Particles in a liquid are more weakly held together and move around.
Particles in a gas move around quickly and randomly, occasionally colliding and bouncing off.
When a liquid or gas is heated, the particles move faster.
Particles are very small, and are not destroyed or made during physical changes.
The overall mass of particles stays the same when a change happens.
Changes of State
A higher temperature means faster particles with more energy.
At absolute zero (-273 oC), the particles stop moving completely.
A change of state takes in or gives out energy.
A solid changes to a liquid (and a liquid to a solid) at the melting point.
A liquid changes to a gas (and a gas to a liquid) at the boiling point.
The boiling point of water is 100oC and the melting point of ice is 0oC, at standard pressure.
Sublimation occurs in a few substances when they change directly between a solid and a gas.
8a. Cells
All living organisms are made of cells which carry out the processes of life
HSE: human reproduction
Assessment: crit B cell model
What are living things made of?
Organisms and cells
All living things are made of cells.
Cells produce more cells by cell division.
Organisms can be uncellular or multicellular.
Multicellular organisms are made of organs.
Humans and other mammals have organs including heart, lungs, liver, brain, skin, eyes, intestines, stomach. Organs are made of different tissues which are groups of similar cells.
Organs work together in organ systems including the respiratory system, the cardiovascular system, the excretory system, the musculo-skeletal system and the nervous system.
Cell structure
Structures of a cell include nucleus, cytoplasm, cell membrane, vacuoles, and mitochondria and each has a different function.
The cell nucleus contains chromosomes made of DNA involved in cell reproduction.
Chromosomes contain information (genes) which determines an organism’s inherited characteristics.
The cell membrane controls the movement of substances into and out of the cell.
The cytoplasm contains cell organelles (such as chloroplasts) which carry out cell functions and also helps move substances around the cell.
Vacuoles store substances inside the cell.
Mitochondria use food and oxygen to produce energy that the cell can use.
Different specialized cells are adapted for different jobs including red and white blood cells, muscle cells, bone cells and neurons.
8b. Reproduction
All living organisms are made of cells which carry out life processes. Humans reproduce when a fertilized egg grows by cell division, implants on the wall of the womb and grows into an embryo, a foetus and then is born as a baby.
HSE: human reproduction
Assessment: crit AB IVF
How do living things grow and reproduce?
Asexual reproduction
The population of a unicellular organisms grows by binary fission.
Cells are specialized within multi-cellular organisms.
Multicellular organisms maintain themselves and grow by cell division and specialization.
Cells reproduce by mitosis, which is splitting into two.
Sexual reproduction
Internal fertilization happens inside the organism, while external fertilization happens outside.
Sexual reproduction in humans involves a sperm and an egg cell (ovum).
The egg and sperm cell each carry half the chromosomes for the nucleus of the fertilized egg.
The human male sex organs include the penis and the testes and the female sex organs include the ovaries, oviduct, womb (uterus) and vagina.
Between puberty and the menopause, the ovaries release an egg approximately every 28 days.
The egg travels down the oviduct where fertilization can happen if it meets a sperm which has swum up through the vagina and uterus.
If the egg is not fertilized, it comes out through the vagina together with some blood and uterus lining in menstruation which lasts approximately 3-7 days.
A fertilized egg (zygote) can implant on the wall of the uterus and grow into an embryo.
The embryo is attached to the uterus through the umbilical chord which contains blood. The umbilical chord is attached to the mother at the placenta where substances pass between the mother’s blood and the child’s blood. Oxygen and food go into the child’s blood and carbon dioxide and waste are removed by the mother’s blood.
Up to 8 weeks, the child is called an embryo and after 8 weeks, when it is starting to form organs, it is a fetus.
The foetus floats in amniotic fluid inside the amnion which protects it.
During birth, the amnion breaks and the baby is born through the vagina.
9. Acids and Alkalis
Substances are classed as acid, alkali or neutral, which allows predictions to be made about their chemical properties.
ENV: classifying substances around us
Assessment: crit DE indicators investigation
How are substances classified using the pH scale and what does this predict about the chemical reactions they take part in?
Acid, Alkali and neutral
Substances can be classified as acid, alkali or neutral.
Different acids and alkalis are strong or weak.
Acids and alkalis can be concentrated or dilute, depending on how much water they are dissolved in.
Some common acids are hydrochloric acid (in human stomachs), sulphuric acid (in car batteries), citric acid (in citrus fruits) and ethanoic acid (in vinegar)
Some common alkalis include sodium hydroxide (in some strong cleaning products), magnesium hydroxide (for upset stomachs) and sodium bicarbonate (in toothpaste)
Indicators
The pH scale describes how acidic or alkaline a substance is, with a number from 1 to 14. The strongest acid is pH1 and the strongest alkali is pH14, with a neutral solution pH7.
Indicators are used to show whether a solution is acidic or alkaline, often changing colour when exposed to acid or alkali.
Different indicators include universal indicator, red and blue litmus and vegetable extracts.
Neutralization
Acids and alkalis are chemical opposites and can neutralize each other.
Neutralization is a reaction between an acid and an alkali producing a neutral solution.
When hydrochloric acid reacts with sodium hydroxide, sodium chloride is made, which is common salt.
Neutralization is used in toothpaste, stomach treatments and fertilizers.
Testing rocks
When an acid reacts with calcium carbonate, carbon dioxide gas is produced, which fizzes. The fizz test shows that a rock contains calcium carbonate, which is the main mineral in limestone and chalk.
10. Electric Circuits
Electric current flows around a complete circuit. A circuit with a lower resistance allows more current to flow, and branches split the current into more than one stream.
HI: scientific models of electricity
Assessment: crit C Quiz game; crit DEF pencil lead investigation
What affects the brightness of a bulb in a cicuit? How do you build a circuit to make a bulb light?
A bulb, battery and wire can be connected so that electric current flows around a circuit.
Circuit symbols are used to represent electrical components in a circuit diagram.
A conductor is a material that allows electric current to flow through it. An insulator blocks the flow of electricity.
Electric current is a flow of charged particles (usually electrons), and is affected by the resistance in a circuit.
The electric current is measured in Amps (A) using an ammeter.
In a battery (cell), a chemical reaction gives electrical energy to electrons (voltage) so that they can flow round a circuit.
In a bulb, current flowing through a narrow wire (filament) heats it up and makes it glow.
In a series circuit the current flows through each bulb in turn. The bulbs are dimmer and the lamps go out if the circuit is broken at any point.
The current at any point in a series circuit is the same.
In a parallel circuit the current splits at a junction to flow through different parts of the circuit. The bulbs are brighter and the branches can be operated independently.
11. Habitats and Adaptations
Living organisms are intimately connected to each other through feeding relationships and nutrient cycles and this determines the populations of different species living in an ecosystem.
ENV: Ecological relationships within the natural and artificial environments.
Assessment: crit AB: Zoos; crit DEF: Lenk ecological study
What does a natural habitat provide for an organism and how does the artificial environment of a zoo mimic this?
Classification
Bacteria and protoctists are made of a single cell (unicellular). Animals, plants and fungi are made of many cells (multicellular).
Plants are autotrophs- they make their own food in their leaves by photosynthesis. Animals are heterotrophs and must consume food.
Each living organism is part of a species. The binomial naming system for species is a latin name e.g. panther tigris.
Ecological relationships
Plants and animals need food, water, etc. to survive and these are provided by their habitat.
Abiotic and biotic factors in a habitat affect the species of plants and animals that are able to survive and reproduce.
Organisms have physical and behavioural adaptations which enable them to survive and reproduce in their habitat.
Living things are intimately connected through feeding and other ecological relationships.
A food chain represents feeding and energy relationships through a food chain. The first trophic level consists of autotrophs (producers) which are usually plants.
Each subsequent trophic level consists in a consumer. The primary consumers are herbivores, and the secondary consumers are carnivores.
Most food chains are three or four trophic levels as energy is lost at each stage. The highest trophic level is inhabited by the top carnivore.
The biomass in a particular area is the total weight of living organisms in that area.
A food web shows interlinked food chains within an ecosystem.
Decomposers recycle material from dead organisms.
12. Science Symposium
One World Science 