Try it: a toilet-roll timeline
- Take a toilet roll. In this model, one sheet stands for five years.
- Choose a grown-up. Let them work out one sheet for every five years of their age, and put a toy there.
- Keep going to about nineteen sheets. The Harbour Bridge was brand new.
- Now unroll the whole roll, outside if you can. The very end is about when castles were new.
- Stand at the far end and look back at your one sheet. Then roll it all up again.
And further?
The pyramids would need about five rolls. The last giant dinosaurs would need a big truck full of rolls.
The start of the Earth would need enough rolls to fill two swimming pools.
You need: one toilet roll and a toy. Rolls differ, and the pack says how many sheets:
with about 190 the end lands near castles. Use the grown-up's real age for step two: one sheet for every five years.
A smaller timeline
If unrolling a whole roll is too much, use a strip of scrap paper. Mark today and a grown-up’s birth, then place family pictures between them. Use evenly spaced folds for equal stretches of time. No one needs to write or count alone.
Grown-up notes
Each line is marked Fact well established,
Model a deliberate simplification, or
Unsure not settled.
Play another way
Pick one invitation, then let your child lead. Watching, pointing or changing her mind all count; there is no answer to pass.
- Find the bridge. Before zooming out, wonder where it will go. Then zoom back in and find it again.
- Ask: “Did the bridge get younger, or did our ruler change?” She can answer by moving the slider.
- Choose a bird you can see today. Remember that birds belong to the dinosaur branch too.
Another connection: Who was here first?
The idea
- FactTime goes back enormously further than anyone can feel. Each stop on the timeline is many times older than the one before, so a single ruler cannot show them all: you have to keep zooming out.
- FactAt every moment the timeline is an honest ruler. Twice as far from the star means twice as long ago. Zooming changes only how many years the whole line stands for.
- FactThe Sydney Harbour Bridge opened in 1932, 94 years before this guide was written.
- FactStone castles were being built in Europe about 1,000 years ago. The Great Pyramid in Egypt is about 4,500 years old.
- FactAboriginal and Torres Strait Islander peoples have lived on this continent for a very long time and still do.
UnsureHow long exactly is still being worked out. Most researchers accept at least 50,000 years, and finds at a rock shelter in Kakadu have been dated to about 65,000 years, a date some archaeologists question. The timeline uses 65,000. The Australia guide explores this story in more detail.
- FactThe "giant wombat cousin" is Diprotodon, the largest marsupial that ever lived: nearly four metres long and up to about 2,700 kilograms. It was a relative of wombats, not a wombat.
UnsureWhen it died out is debated; estimates run from about 50,000 to about 25,000 years ago. People and Diprotodon shared the continent for some of that time.
- UnsureThe oldest fossils usually counted as our own species are about 300,000 years old, from Morocco. Not every researcher agrees they belong to our species, and our beginnings were probably spread across Africa over a long time rather than in one place and moment.
- FactThe last of the giant dinosaurs died out about 66 million years ago. Birds are living dinosaurs, which is why the caption says "giant dinosaurs" and not just "dinosaurs".
- FactThe Earth is about 4.5 billion years old (4.54 billion is the usual figure).
What the pictures simplify
- ModelDad's age. "When Dad was a baby" is drawn at 40 years ago. Say whatever is true in your family; the idea is the same.
- ModelA handful of stops. Nine things stand in for all of history. Almost everything is left out, and most stops come from just a few parts of the world.
- ModelThe pictures are not to scale. A baby and a dinosaur are drawn the same size, and they shrink as they move towards now only so the line stays readable.
- ModelPeople from long ago are drawn as plain silhouettes, because nobody knows what any of them looked like.
- ModelThe new Earth is drawn glowing hot. It was molten at times early on, but the picture is a cartoon.
- Model"The oldest people alive were babies" when the bridge opened: true of people now in their mid-nineties, not literally the single oldest person.
- ModelThe paper roll. One sheet is five years. A roll is taken to be 190 sheets, which puts castles at the end. The truck and the swimming pools are rough estimates: about 70,000 rolls for the dinosaurs and nearly five million for the Earth, at roughly a litre a roll.
Questions she may ask
- How do they know how old things are? ModelFor the last few thousand years people wrote things down. Before that, scientists read natural clocks: layers that build up one a year, and tiny bits inside rocks and bones that change at a steady rate.
- Did dinosaurs live when Grandma was little? FactNo. On the paper roll, Grandma is a few sheets away and the dinosaurs are a truck full of rolls away.
- Did people see dinosaurs? FactNo person ever saw a giant dinosaur. They were gone long, long before the first people. People see living dinosaurs every day: birds are the surviving dinosaur branch.
- What was there before the Earth? FactThe Sun and the Earth formed from a huge cloud of gas and dust. The universe itself is about three times older than the Earth.
UnsureWhat, if anything, came before the universe: nobody knows yet.
- Will it keep going? FactYes. The star marked "now" keeps moving. One day today will be long ago.
Words this guide teaches
Timeline: a line that shows when things happened, with now at one end. Zoom out: step back so you can see more at once.
Ancient: very, very old.
Go further
The Australian Museum in Sydney (1 William Street) has dinosaur skeletons and, in its Surviving Australia gallery,
life-sized models of Australia's giant animals including Diprotodon. General admission is free. Check
the museum's website for opening hours and which galleries are open.
Sources
Checked November 2026. The dates for the bridge, castles, the pyramids, the dinosaurs and the universe are
standard figures recalled rather than taken from a linked page.