How Big, Really?

The Time Travellers Atlas · timetravellersatlas.com

Name

Class

Date

“Twelve metres long” means almost nothing until you stand next to something twelve metres long. This sheet turns dinosaur measurements into things you can actually picture — and then walk out and measure.

1Collect your data

Open Scale Lab at timetravellersatlas.com. Choose four dinosaurs — make sure one is very large and one is very small.

Dinosaur	Length (m)	Weight (kg)

2Order them

Write your four dinosaurs from shortest to longest.

Now write them from lightest to heaviest.

Are the two lists in the same order? If not, that is the interesting part — write down which dinosaur moved, and see if you can suggest why.

3How many of you?

Measure your own height in metres, to one decimal place. A partner and a tape measure will do it.

My height

Your longest dinosaur is how many times your height? Show your working.

working

Making it real

How Big, Really? · Page 2

4Pace it out

Go outside, or into a hall or corridor. Measure the length of your largest dinosaur on the ground — a tape measure, a trundle wheel, or counting your own paces once you know how long one pace is.

Dinosaur
Its length
What it reached to

Draw what the far end lined up with — a door, a tree, a fence post, the end of the field.

the far end

5The weight problem

A family car weighs roughly 1,500 kg.

How many cars would balance your heaviest dinosaur? Show your working, and round sensibly.

working

6The one that surprised you

Which dinosaur was a different size from what you expected, and why do you think you expected wrong?

Teacher notes

How Big, Really? · Ages 8–12 · 50–70 minutes, or two shorter sessions

What this sheet is for

This is a measurement and proportional-reasoning lesson wearing a dinosaur costume. Students collect real data, order it two ways, calculate multiples, and — the part that makes it stick — take the number outside and mark it on the ground. Children who can recite “Argentinosaurus was 33 metres long” are frequently astonished when they walk it.

Question 2 hides the real science. Length order and weight order are not the same, because animals are not scaled copies of one another: a long slender predator can be lighter than a shorter, bulkier herbivore.

Figures from the atlas (for checking)

Dinosaur	Length	Weight
Argentinosaurus huinculensis	33 m	70,000 kg
Mamenchisaurus sinocanadorum	26 m	25,000 kg
Spinosaurus aegyptiacus	14 m	7,400 kg
Tyrannosaurus rex	12.3 m	8,400 kg
Giganotosaurus carolinii	12.5 m	7,300 kg
Velociraptor mongoliensis	2 m	15 kg
Microraptor gui	0.8 m	about 1 kg

The example worth pointing out: Spinosaurus is longer than T. rex (14 m against 12.3 m) but lighter (7,400 kg against 8,400 kg). Giganotosaurus is longer than T. rex too, and lighter again. Length does not decide weight.

Worked examples

Q3 — a 1.4 m student against Argentinosaurus: 33 ÷ 1.4 ≈ 23.6, so about 24 children head to toe.
Q5 — Argentinosaurus at 70,000 kg ÷ 1,500 kg ≈ 46.7, so about 47 cars. T. rex: 8,400 ÷ 1,500 = 5.6, so between five and six.
Accept any sensible rounding. “About 47” and “nearly 50” are both good answers; 46.666… copied off a calculator is worth a conversation about what precision is for.

Differentiation

Support: supply the four dinosaurs rather than letting students choose, and give the division as repeated subtraction or a number line. The outdoor task works at any level.
Extension: ask for weight per metre of length (kg/m) and rank by that instead. Argentinosaurus is about 2,120 kg/m; T. rex about 683; Microraptor about 1.25. This is density of build, and it separates sauropods from theropods cleanly.
Further extension: if a dinosaur were scaled to twice the length, what happens to its weight? Not double — roughly eight times, because weight follows volume. This is the square-cube law, and it is why there is an upper limit on land animal size at all.

Practical notes

33 metres needs a corridor, hall or field. If space is short, do it at half scale and have students double every measurement — which is more mathematics, not less.
A trundle wheel is ideal. Failing that, have each student measure one pace, then count paces.
Weights of extinct animals are estimates from bone dimensions and vary between studies. Saying so is honest and is itself a nature-of-science point.

Curriculum links

Curriculum	Strand
New Zealand	Mathematics — Measurement: units, estimation, comparison. Number: multiplicative thinking, ratios. Statistics: collecting and ordering data.
England (KS2)	Measurement — estimate, compare and calculate; convert units. Ratio and proportion. Statistics — interpret and present data.
NGSS / Common Core (USA)	CCSS.MATH 4.MD.A.1–2, 5.NF.B.5 (scaling), 6.RP.A.3 (ratio reasoning).
Australia	Mathematics — Measurement and Geometry: using units of measurement. Number and Algebra: proportional reasoning.