Nutrition and the Digestive System

Learning Intention: Students will know the five groups of nutrients and how they contribute to a healthy diet. They will investigate the composition of various foods using food testing experiments, including various bush foods from the school garden and beyond. They will compare the diet of people living in Australia 10,000 years ago with their own diet.

Success Criteria: Students will produce a poster, video or other artifact that demonstrates their understanding of nutrition today and in Australia’s past. Their product will explain the five nutrients (carbohydrates, proteins, lipids, vitamins and minerals) and the foods in which these nutrients are found. The importance of fibre and water in the diet will also be discussed.

Links to AusVELS: “Multi-cellular organisms contain systems of organs that carry out specialised functions that enable them to survive and reproduce.”
“Energy appears in different forms including movement (kinetic energy), heat and potential energy, and causes change within systems.”
“Also, links to cross-curricular priorities – Aboriginal and Torres Strait Islander histories and cultures.”

This term we started a new topic of work – nutrition and the digestive system. We have discussed the five main nutrients and the importance of water and fibre in a healthy diet. We have also used the model human torso and watched videos to understand how the digestive system works. Mr John Pearce (@mrpbps on Twitter) has shared this wonderful hands-on “Tour of the Digestive System” that we may try too. Parts of Plants we Eat.

We will learn how energy is measured and the energy content of some different foods, using the nutritional information of food labels. Our next tasks will include using various tests to determine what nutrients make up different foods. We will do the following tests:

1.Brown paper or Emulsion test for fats and oils (lipids).
2.Iodine test for starch.
3.Benedict’s solution and heat for glucose (sugar).
4.Copper sulphate (10 drops) and sodium hydroxide (5 drops) for protein.

We will then collect some bush foods from the school garden and Apex Park and test those foods for starch, protein, sugars and lipids. You will then create a product that compares the diet of people in Australia 10,000 years ago to your diet. You may have heard of the “Paleo diet” (also called the “caveman” or “stone-age” diet). It consists mainly of fish, meats, eggs, vegetables, fruit, fungi, roots and nuts and excludes grains, legumes, dairy products, potatoes, salt, sugar and processed oils. What would Bear Grylls survive on in the Australian Bush?

Some useful links:

 

Acids and Bases

Learning Intention:
Students will understand that the pH scale ranges from 1 (acid) to 7 (neutral) to 14 (basic). They will understand that acids release a hydrogen ion in solution and alkaline substances release an hydroxide ion. Substances can be tested using an acid-base indicator such as litmus paper or purple cabbage indicator. The colour change that occurs is another example of a chemical reaction.

Success Criteria:
Students will make an acid-base indicator by boiling red cabbage and straining the liquid. They will then test a range of household substances, including cleaning products, vinegar and lemon juice and determine whether they are acids or bases. Students will then use indicator paper to check their results and arrange the substances from low pH (most acidic) to high pH (most basic).

Our assessment for this unit of work will be a test on Thursday during period 5. Use Pages 76 and 77 of your textbook for revision. You may like to try this quiz at Quiz Revolution. These videos at How Stuff Works are also good revision for the test.

Seven Reactions that will fascinate your science class – Five of these reactions are chemical reactions (what are the indicators for a chemical reaction?) and two are physical changes. Which two are physical changes?

Sulfuric acid in sugar (video)  – What are the signs that this is a chemical reaction?

Sodium metal in water (video) – What are the signs that this is a chemical reaction?

Chemical Reactions – Rusting

Learning Intention: Students will understand that rusting is another type of chemical reaction, in which the products of the reaction are different to the reactants. They will also learn about the process of planning and conducting an experiment, devising an hypothesis and using a control with variables.

Success Criteria: Students will plan and conduct an experiment that tests an hypothesis about rusting.

You will be familiar with ‘rust’ as the orange/brown corrosion that affects some metals. Farmers, engineers, sailors and car-makers are all very aware of the economic impact of rusting. Rusting is a chemical reaction that occurs when metals are exposed to moisture and the air. How Stuff Works has a good article about rust – “How does rust work?”. Read pages 60 and 61 in your text book. Your task is to devise an experiment to investigate rusting. You may like to test the effect of the saltiness of water on the time taken for an iron nail to rust. You may like to test some methods that are used to reduce or prevent rusting. Follow these steps:

  1. Write an hypothesis – a theory about rusting that you want to test. For example, “The greater the concentration of salt, the quicker iron will rust.”
  2. What will be the ‘control’ and the ‘variable’ in your experiment?
  3. Write a list of materials and equipment that you will need to complete the test. Submit your list of requirements to me so we can be sure we have everything you will need.
  4. Formulate a method that describes exactly what you need to do – make sure someone else can use this method to repeat the experiment in exactly the same way you have done.
  5. In your method you need to include how you will record your results – will you measure mass, time, volume, temperature or some other factor/quantity?
  6. Undertake your experiment, recording your results.
  7. Include a discussion of your findings in your report. Were there any sources of error or unexpected results?
  8. Write a conclusion that refers to your original aim/hypothesis. Did you prove or disprove your hypothesis? Do you need to do further experimentation?

Making Paper from Grass

 

Paper made out of banana tree

You use stacks of paper every day but do you know how it’s made? Paper has been made since 105 AD in China, but other materials such as papyrus (in Egypt), parchment and vellum (various grades of mammal skin) were used in other parts of the world prior to this. Find out more about the history of paper at Wikipedia.

In Sri Lanka, a fair trade company is making paper from elephant pooh! In that country, humans are encroaching on elephant habitat, cutting down trees for fire wood and shooting and killing elephants that come looking for food. This company, “Mr. Ellie Pooh” aims to create employment and encourage villagers to see the elephants as an asset rather than a threat.

Compared to using virgin wood, paper made with 100% recycled content uses 44% less energy, produces 38% less greenhouse gas emissions, 41% less particulate emissions, 50% less wastewater, 49% less solid waste and — of course — 100% less wood.

This week we are making paper from grass in six steps:

  1. Cut the grass and grind it with the mortar and pestle
  2. Add caustic soda to release the cell contents
  3. Wash and rinse to remove chemicals and cell contents
  4. Add bleach and bring to the boil
  5. Wash and rinse to remove the bleach
  6. Form the paper

Which of these steps are physical changes and which are chemical changes?

The Carbon Cycle

Created using Comic Life

Learning Intention: Students will understand the processes involved in the carbon cycle – photosynthesis, respiration, decomposition, combustion and fossil-fuel formation.

Success Criteria: A product that demonstrates their understanding by providing an explanation of each of these processes.

Your assessment task for this unit of work is to produce an artefact that explains your understanding of the carbon cycle. It might be a poster, video, Voicethread, cartoon or slideshow. You could use Comic Life, ToonDoo, a common-craft style video or another tool. Make sure you include the following processes:

  • Photosynthesis – green plants use sunlight to convert carbon dioxide and water into carbohydrate (glucose) that is used by all other living organisms as the source of food. (absorbs CO2 and H2O and releases O2)
  • Respiration – all living organisms (with the exception of a few bacteria) use oxygen to convert carbohydrates into energy, releasing carbon dioxide and water into the atmosphere. (Requires O2 and releases CO2 and H2O)
  • Decomposition – Bacteria and fungi break down organic matter (leaves, wood, dead animals etc) into carbon dioxide and water during respiration.(Requires O2 and releases CO2 and H2O)
  • Fossil Fuel formation – Oil, coal and gas are formed after millions of years under extreme pressure and high temperatures, from once living organisms such as trees and microscopic algae.
  • Combustion – wood, gas, oil, coal and other carbon-containing compounds can be burnt with oxygen to produce carbon dioxide. (Requires O2 and releases CO2 and H2O)

Some useful resources:

Elements and Compounds

Image Source

So far this year, you have learned about the following:

  • An atom consists of positively charged protons and neutrons with no charge in a nucleus in the centre of the atom and much smaller electrons, which are negatively charged and on the outside of the atom.
  • Molecules are tiny particles made up of more than one atom. A water molecule is made up of two hydrogen atoms and one oxygen atom.
  • Elements are pure substances that are made up of one type of atom. There are 92 naturally occurring elements and some man-made elements.
  • Compounds are substances made up of more than one type of atom, tightly bound together. They can look and behave very differently to the elements that they are made up of.
  • Elements are organised in the periodic table according to the number of protons in their nucleus. Hydrogen is #1 because it has one proton, helium is number 2 because it has 2 protons etc.
  • Each column of the periodic table contains elements with characteristics in common – the noble gases in Group 8 are all very non-reactive elements for example.

Your assessment task for this unit of work is to produce an artefact that explains your understanding of the carbon cycle. It might be a poster, video, Voicethread, cartoon or slideshow. You could use Comic Life, ToonDoo, a common-craft style video or another tool. Make sure you include the following processes:

  • Photosynthesis – green plants use sunlight to convert carbon dioxide and water into carbohydrate (glucose) that is used by all other living organisms as the source of food.
  • Respiration – all living organisms (with the exception of a few bacteria) use oxygen to convert carbohydrates into energy, releasing carbon dioxide and water into the atmosphere.
  • Decomposition – Bacteria and fungi break down organic matter (leaves, wood, dead animals etc) into carbon dioxide and water during respiration.
  • Fossil Fuel formation – Oil, coal and gas are formed after millions of years under extreme pressure and high temperatures, from once living organisms such as trees and microscopic algae.
  • Combustion – wood, gas, oil, coal and other carbon-containing compounds can be burnt with oxygen to produce carbon dioxide.

Year 8 Science: Atoms and Molecules

Learning Intention: Students will be able to recognise the structure of atoms and molecules and understand some of the features of the periodic table. They will know that elements are pure substances made up of a single type of atom.

Success Criteria: You will be able to define atoms, molecules, elements and compounds. You will be able to draw a labelled diagram of an atom and explain why elements are arranged in the periodic table in rows and columns.

As you discovered this week, chemistry is everywhere! All substances are made up of atoms and molecules whether they be gases, liquids or solids. Some are pure substances (elements) made up of one type of atom, but most are compounds, made up of molecules of atoms of different kinds. We will complete several experiments next week, that show that a compound can be very different from the elements from which it is comprised. For example, hydrogen(H2)  and oxygen(O2) are colourless gases, but H20 (water) is a colourless liquid. Carbon (C) can be like charcoal, graphite or diamond, but carbon dioxide (CO2) is a colourless gas.

More information about atoms and elements at BBC Bitesize and the NDT Resource Centre.

Year 7 – Separating a Mixture

Last lesson the Year 7 students were given a mixture of salt, sand, iron filings and rice. Their task was to separate the mixture into it’s components, trying to conserve as much of the material as possible. This is the slideshow that previous year’s students prepared, showing how they went about the task.

Chemical Energy

Learning Intention: Students will understand the relevance of specific chemical reactions to everyday life and be able to describe the usefulness of those reactions to society.

Success criteria: Students will produce a poster, slideshow or video that investigates and describes a specific chemical reaction and it’s usefulness in our lives.

Your task is to research one of the following materials and how they can react to produce useful results – a release of heat, a new product or a portable source of energy for example. Find out how these materials are extracted or produced, the useful reaction that occurs and how this reaction benefits society. Are their any disadvantages of this reaction? (eg. greenhouse gases produced, finite resources being used or toxic by-products?

  1. Fossil Fuels (oil, coal or gas – choose one) – combustion
  2. Dynamite explosions
  3. Electrolysis to allow silver plating, copper plating etc
  4. Batteries – (car battery, torch battery, lithium rechargable battery etc)
  5. Biofuels – ethanol for sugar cane or corn, methane from effluent or garbage, biodeisel from abbatoir waste, algae or waste oils)

This project is due next Monday, 14th May and will be assessed for your end of term report.

 

 

Exothermic and Endothermic Reactions

Image Source

Learning Intention: Students will understand the meaning of exothermic and endothermic reactions.

Success Criteria: Students will be able to identify exothermic and endothermic reactions and give examples of each. They will be able to explain why these processes to considered to be exothermic or endothermic.

Endothermic reactions absorb energy, causing a decrease in temperature (eg. photosynthesis, melting and evaporation all require energy to be added to the system). Exothermic reactions release energy, causing an increase in temperature (Combustion, freezing, and condensation release energy from the system).

Mr Kent’s Chemistry page has some excellent examples of exothermic and endothermic processes and chemical reactions. We will be conducting four experiments in class and measuring the temperature change to determine which are endothermic and which are exothermic reactions. Leave comment below about what you found from your experiments. Can you think of any examples of exothermic and endothermic processes from home?