How Scientific Knowledge Changes: a skill companion
A small set of reusable sheets that grow one Human Endeavour idea: scientific knowledge is the best explanation of the evidence so far, and new evidence, a new tool or a different perspective can change it, even after a long time. Print the scaffolds once and slot them into the science lessons you already teach.
What a skill companion is
Human Endeavour ideas are not a topic of their own. They grow inside the science units a class teaches all year, such as Classifying Living Things, Energy Flow in Ecosystems, Earth, Sun and Moon, Balanced and Unbalanced Forces, The Particle Model of Matter, and Pure Substances and Mixtures. So this pack is not a full term of lessons. It is three reusable scaffolds, a map of where they fit, and a short stand-alone lesson for teaching the idea on its own first.
Start here: five minutes
- Read the pairing map on the next page: it shows a change in knowledge for each Year 7 topic, and the scaffold to reach for.
- Print the organiser whenever a topic meets an idea that changed, and the case-study sheet once per student.
- Cut out the cards once. They are reused all year, whenever a news story or a class result raises the question of whether an idea should change.
- Open the free interactive unit on your board when you want a worked example of the idea.
- Run the one-page mini-lesson first if you want to teach the idea before folding it into a topic.
No science background needed
Each scaffold explains itself in plain words, and the answer sheet gives a model organiser for the unit’s story of drifting continents, the case-study answers, the card key with a reason for each, a model answer for every Year 7 topic and a quick three-level guide. In Year 6, students examined why advances come from people working together and building on earlier work. The step up in Year 7 is change itself: how new evidence or a different perspective can revise even long-accepted knowledge, and why that is a strength of science, not a weakness.
Slot the idea into your science lessons
Every science unit holds an idea that was once explained differently. This map shows one in each Year 7 topic, what changed it, and which scaffold to reach for. You do not run these as extra lessons; you fold them into the science you teach.
| When you teach | A change in knowledge | What changed it | Scaffold |
|---|---|---|---|
| Classifying Living Things (AC9S7U01) | Accepting that platypuses lay eggs | A different perspective, then new evidence: Aboriginal people had long said so and were not believed, until eggs were found with their help in 1884 | Organiser, then the cards |
| Energy Flow in Ecosystems (AC9S7U02) | Where the energy in a food web starts | A new tool, then new evidence: in 1977 a deep-sea submersible found animals crowded around hot springs on the sea floor, fed by microbes that make food from chemicals | Organiser |
| Earth, Sun and Moon (AC9S7U03) | Whether the Earth or the Sun is at the centre | A new tool, then new evidence: in 1610 Galileo’s telescope showed Venus going through a full set of phases, which fits Venus circling the Sun | Organiser |
| Balanced and Unbalanced Forces (AC9S7U04) | Why moving things slow down | New evidence and a new way of looking: Galileo’s rolling-ball experiments, then Newton’s first law in 1687, showed that friction is what slows things down | Organiser, then the cards |
| The Particle Model of Matter (AC9S7U05) | Whether the particles of matter are real | New evidence: in 1908 Jean Perrin measured the jiggling of tiny grains in water, and his results matched Einstein’s particle explanation of 1905 | Organiser |
| Pure Substances and Mixtures (AC9S7U06) | Whether water is an element | New evidence: in the 1780s Henry Cavendish and Antoine Lavoisier made water by burning hydrogen, so water is a compound of hydrogen and oxygen | Organiser |
| Any science topic | A new finding in the news | Ask whether it is checked new evidence, something to check first, or no reason at all | The case study, then the cards |
The three moves, and the picture that backs each one
When you want a worked example on the board, open the interactive unit and use the picture that matches the move.
- Follow a model as each new piece of evidence revises it: “The changing model of the atom”.
- Tell real evidence from findings that only sound related: “Did the evidence support drifting continents?”.
- See the measurement that settled a long argument: “Age of the Atlantic sea floor with distance from the ridge”.
How the scaffolds build the idea
The organiser sets out any change in knowledge: what was accepted before, what changed it, and what is accepted now. The case study follows Robin Warren and Barry Marshall in Perth, whose new evidence about stomach ulcers took years to be accepted. The cards sort reasons by whether they should change what scientists accept: a good reason, something to check first, or not a reason at all.
How did the knowledge change?
Pick an idea from our topic that science once explained differently. Write what was accepted before, what changed it and what is accepted now, then answer the questions.
| Accepted before | What changed it | Accepted now |
|---|---|---|
| □ new evidence□ a new tool□ a different perspective |
Think about it
Teacher note: the unit’s story of drifting continents fills the organiser well as a first go; a model is on the answer sheet.
The bacterium no one believed in
For most of the 1900s, doctors were taught that a stomach ulcer, a painful sore in the lining of the stomach, came from stress, spicy food and too much stomach acid. Medicines that cut down the acid eased the pain, but the ulcers often came back. Doctors were also taught that bacteria could not live for long in the strong acid of the stomach.
In 1979, Robin Warren, a pathologist at Royal Perth Hospital, kept seeing small curved bacteria under his microscope in samples from inflamed stomachs. In 1981, a young doctor, Barry Marshall, joined him. For months they could not grow the bacteria in the lab, until some dishes were left in the incubator over the five-day Easter break in 1982, longer than usual, and the bacteria grew.
Many stomach specialists still did not accept that bacteria could cause ulcers. In 1984, Marshall drank a culture of the bacteria. Within about a week he was ill, and a sample from his stomach showed it was inflamed and full of the bacteria. Studies in many countries then found that antibiotics cured most ulcers, and that the ulcers rarely came back. In 1994, experts in the United States advised doctors to treat ulcers with antibiotics, and in 2005 Marshall and Warren were awarded the Nobel Prize in Physiology or Medicine.
| New evidence | |
| A new method | |
| A different perspective | |
| Checking by others |
Teacher note: Marshall’s experiment on himself was risky. Today, research on people, even on yourself, must first be approved by an ethics committee.
Should it change what scientists accept?
Cut out the cards and lay down the three grey heading cards. For each card, decide whether it is a good reason to change (or to keep) what scientists accept, something to check first, or not a reason at all. Be ready to say why.
Teacher note: four cards go in each pile. The answer sheet lists which is which, and why.
What is in the box?
Use this stand-alone lesson to teach the idea on its own, before you fold it into a science topic. Each group builds a model of what is inside a closed box, changes it as each new tool brings new evidence, and compares it with a group that had the same box. The lids stay on, just as scientists who study atoms can never open one.
We are learning to
- build a model that fits the evidence so far,
- change a model when new evidence or another group’s view does not fit it,
- explain why a model that changes is a better model, not a failure.
Success criteria
- I can point to the clue that made us change our model.
- I can say how sure we are of our final model, and what would change it.
You need
- closed boxes made before the lesson, two of each kind: shoeboxes taped shut with one or two objects inside, such as a marble, a steel washer or a wooden block, and in some a card wall taped across the inside; two pencil-sized holes in each lid,
- for each group, a fridge magnet, a pencil, and kitchen scales with an empty box of the same kind to compare,
- the cards (scaffold 3), one set per table, and the free interactive unit on your board, if you have one.
Safety: push the pencil gently, and only through the holes already in the lid. No sharp tools.
Lesson flow (about 30 minutes)
| 5 min | Tilt and listen Groups tilt, roll and listen to their box, then draw model 1 of what is inside. Ask: “What makes you think that? What can you not tell yet?” |
| 10 min | New tools Give out one tool at a time: the magnet, then the scales with the empty box, then the pencil to push gently through the holes. After each one, groups keep or change their model, drawing models 2 and 3. Ask: “Which clue made you change your model? Which part stayed the same?” |
| 10 min | Another view The two groups with the same kind of box show each other their models and the clues behind them. Each group may change its model again. Ask: “What did the other group notice that you did not? Did you change because of a clue, or because they sounded sure?” |
| 5 min | Keep the lid on Leave the boxes closed, and tables sort the cards under the three heading cards. Ask: “Scientists cannot open an atom. How sure can we be of our model, and what would change it?” |
Running it shorter? Use the magnet and the scales only, and sort the cards in your next science lesson.
Watch for these ideas
- Thinking a model that changed was wrong all along and useless, rather than the best fit for the clues so far.
- Changing a model to match another group because they sound sure, not because of a clue.
- Expecting to open the box at the end: scientists often never see the thing they model.
Make it easier, make it bigger
- Easier: put one object in each box, and ask one question with each tool.
- Bigger: groups design one more test that would tell two models apart, and say which result would change their minds.
Answers and look-fors
The next sheet has a model organiser for drifting continents, the case-study answers, the card key, a model answer for each Year 7 topic, and a quick three-level guide.
Answers and look-fors
Organiser: drifting continents
| The idea | Whether the continents move |
| Accepted before | In the early 1900s most geologists held that the continents had always stayed where they are, and explained matching fossils across oceans by land bridges that later sank. |
| What changed it | Alfred Wegener’s evidence from 1912: coastlines that fit together, and matching rocks and fossils across oceans, gathered by a scientist trained in astronomy and weather, not geology. Then, from the 1950s, ships measured the sea floor: youngest at the ridge, older further away. All three boxes ticked: new evidence, a new tool, a different perspective. |
| Accepted now | The continents ride on huge moving plates; new sea floor forms at mid-ocean ridges and spreads outwards. |
| Who, and when | Alfred Wegener, 1912; ship surveys of the sea floor, 1950s and 1960s. |
1. No one could say what force could move a whole continent, and land bridges seemed to explain the fossils. 2. The fitting coastlines, the matching rocks and fossils, and why the sea floor is youngest at the ridges. 3. Yes. Some said Wegener was not a geologist (not a reason); others asked what force could move a continent (a fair reason to check first). 4. Yes, if new evidence turns up that the plate model cannot explain; scientists are still working out exactly what drives the plates.
Case study: the bacterium no one believed in
1. Ulcers came from stress, spicy food and too much acid, and bacteria could not live in the stomach. 2. Curved bacteria in samples from inflamed stomachs, the bacteria grown in the lab, Marshall’s illness after drinking them, and ulcers cured by antibiotics. 3. Fair: the claim went against a great deal of earlier work and came from one small study, so others needed to repeat it. Not fair: rejecting it because Marshall was young or not a stomach specialist, or because it was not what they had been taught. 4. Studies in many countries found that antibiotics cured most ulcers for good. 5. 15 years, from 1979 to 1994. 6. New evidence: the curved bacteria in inflamed stomachs. A new method: leaving the dishes longer, which let the bacteria grow. A different perspective: a pathologist and a young doctor questioned what stomach specialists had been taught. Checking by others: studies in many countries tested the antibiotics.
Reason cards
| Card | Pile | Why |
|---|---|---|
| A | Check first | A single run could be a mistake. Repeat it first. |
| B | A good reason | Others repeated it, and it held up. |
| C | Not a reason | Fame is not evidence. |
| D | Not a reason | Popularity is not evidence. |
| E | Check first | It needs more sightings, or an animal others can examine. |
| F | A good reason | A different perspective brought new observations, and they were checked. |
| G | Check first | Too few people and no fair comparison. A bigger, fair test is needed. |
| H | Not a reason | Who someone is does not make an idea right or wrong. Geologists said this about Wegener. |
| I | A good reason | Many careful measurements that agree. |
| J | A good reason | The patients’ view pointed to something new, and a large study checked it. |
| K | Not a reason | Age alone does not make an idea right. |
| L | Check first | The instrument may be faulty. Check it before trusting the reading. |
Cards F and J are the different perspectives: in each, people who see the world differently noticed something new, and it was checked before anyone changed their mind.
What a good answer sounds like
| Topic | A change | How it changed, at standard |
|---|---|---|
| Classifying Living Things (AC9S7U01) | Accepting that platypuses lay eggs | European scientists did not believe Aboriginal people who said that platypuses lay eggs. In 1884 William Caldwell, working with Aboriginal people in Queensland, found the eggs, and platypuses and echidnas are now grouped as monotremes, mammals that lay eggs. |
| Energy Flow in Ecosystems (AC9S7U02) | Where the energy in a food web starts | Food webs were thought to begin with sunlight. Deep-sea vents showed food webs that begin with microbes using chemicals, so the idea was widened, not thrown out: most food webs still begin with sunlight. |
| Earth, Sun and Moon (AC9S7U03) | Whether the Earth or the Sun is at the centre | The telescope showed things no one could see before, such as the full set of phases of Venus, which the Earth-centred model of the time could not explain, so the Sun-centred model gained support. |
| Balanced and Unbalanced Forces (AC9S7U04) | Why moving things slow down | For about 2000 years many people followed Aristotle: a moving object needs a push to keep moving. Galileo saw that friction slows things, and Newton’s first law says an object keeps moving unless an unbalanced force acts on it. |
| The Particle Model of Matter (AC9S7U05) | Whether the particles of matter are real | Some leading scientists doubted that atoms and molecules were real. Perrin’s measurements matched what Einstein had predicted for water particles bumping the grains, and nearly all the doubters were won over. |
| Pure Substances and Mixtures (AC9S7U06) | Whether water is an element | For more than 2000 years water was thought to be an element. Making water by burning hydrogen showed that it is a compound of hydrogen and oxygen; Lavoisier named hydrogen from the Greek for “water-former”. |
A quick three-level guide
| Move | Working towards | At standard | Beyond |
|---|---|---|---|
| Describe the change | says that an idea changed | says what was accepted before, what changed it, and what is accepted now | explains what the new idea explains that the old one could not |
| Explain what drove it | names a person or a date | names the new evidence or the different perspective, and how it was checked | explains why the change took time, and why waiting for checks was fair |
| Judge reasons to change | treats every new claim the same | tells checked evidence from claims to check first and from things that are not reasons | explains why knowledge that can change is more trustworthy, not less |
A student at standard explains how new evidence or a different perspective changed an idea, and why the change made the knowledge more reliable. The idea grows all year, so keep the organiser and the cards coming back in every topic.