Activity Goals:
— To introduce students to the range of sizes among dinosaurs and other prehistoric animals.
— To help students visualize the actual sizes of these animals by projecting images in your classroom.
— To help students gain an intuitive feel for the mathematical process of scaling.


Animal Overhead Sheets, Cardboard, Cellophane tape, Overhead projector, Long extension cord, Rolling cart, Meter stick or measuring tape, Transparency overhead sheets

Photocopy each of the Animal Overhead Sheets onto individual transparency sheets. Using cardboard and cellophane tape, make flap that covers the meter line and identification name (answer) on each Overhead Sheet. Place an overhead projector, with a long extension cord, on a rolling cart so that it may be easily wheeled around your classroom. Practice projecting the images to correct size ahead of time. You may need a larger room.


1) Explain that prehistoric animals, including dinosaurs, came in many sizes. Today students will have the chance to guess the actual sizes of some of these animals.

2) Move the desks if necessary to make an aisle so that you can roll the overhead projector cart closer and farther from the wall. Place one of the Overhead Sheets into the projector. Be sure that the cardboard flap is covering the answer. Project the image onto a clean, light- colored wall in our classroom.

3) As you move the projector closer and farther from the wall, changing the size of the projected image, have your students decide how big the animal actually was.

4) Once they have agreed upon a size, check their estimate by removing the flap so that the answer box is also projected onto the screen. There is a line drawn on it labeled "1 Meter". Have a student helper hold the meter stick near that line while you move the projector back and forth until the line is actually one meter long on your wall. At that point, the animal will also be the correct size.
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Who was surprised at how little or how big some animals were?

Were all dinosaurs big?

Were dinosaurs the only big animals to ever live?


Key to Overheads:
The following prehistoric animal images can be printed out. Click to view, then print.
Sheet #1: Coelophysis — a small, carnivorous, Triassic dinosaur.
Sheet #2: Iguanodon — a large, herbivorous, Cretaceous dinosaur.
Sheet #3: Dinohyus — a large, pig-like, carnivorous, Miocene mammal.

Teacher Tip:
Save the largest dinosaur until last. You may not be able to fit the entire dinosaur on your wall, so try showing only part of it to actual size (maybe the leg). Every time I do this activity, kids rush up to the wall to compare themselves to the gigantic leg.