Do you have a collection? Shells, stamps, coins, dolls, butterflies? Many people do. But with most collections, there isn't much you can do with your collection besides look at it.

That's not the case for model railroaders. Many enthusiasts say that movement is what sets model railroading apart, and that the best part of their hobby is running a train through a finished scene. You can experience the thrill for yourself and learn more about this popular hobby when you visit Tucson's Gadsden Pacific Division Toy Train Museum.

There are three major divisions within the hobby of model railroading. Some collectors are interested in toy trains, like the Lionel or American Flyer train sets we often think of as being set up under Christmas trees in years gone by. Garden railroaders are another group. They enjoy creating outdoor settings for their trains, which are bigger and more rugged than traditional toy trains.

The most popular category, however, is scale-model railroading. Scale-modelers set out to duplicate the locomotives and cars used by real railroads, right down to the rivets and bolt heads.

The goal is to create a miniature world, known as a layout, that features not only the trains but a complete and precise replica of their surroundings.

Trains are differentiated by their scale and their gauge. "Scale" refers to the comparative ratio between a miniature and its full-size prototype. The second aspect of a model's size, "gauge," refers to the space between the rails of the track. The most popular size is approximately half the size of O gauge models, and so is called "HO," for "half of O." Look at the model train scales chart to get an idea of the sizes of popular model trains.

Model railroading is a great way to combine interests in science and art. You can learn about woodworking, electricity and physics, as well as working with plaster and other art materials. You may also find yourself drawn into the history of railroading, learning about how real railroads work and the role they have played in our history and economy.

Tune Up Your Mind

Look for these books and related materials:

● "Steam, Smoke, and Steel: Back in Time With Trains" by Patrick O'Brien (Charlesbridge Publishing, $16.95)

● "The Big Book of Trains" edited by Jane Yorke (DK Publishing, $14.99)

● "All Aboard!" CD by John Denver (Sony Music, $13.98)

Model Railroader magazine

Discovery Detours

The GPD Toy Train Museum has five large layouts (surfaces that contain track, buildings, and the landscapes comprising the model train environment), in a variety of scales. Many of the trains produce smoke and have whistles and bells.

Some of the new trains are remote controlled and are automated to produce sounds recorded from real trains as well as station announcements. The toy trains running on the layouts on any given day may represent toys from the early 1900s to brand new trains. They may be steam or diesel engines.

Almost all are toy models of real trains that were operated by American railroads since the early days of railroading in this country. Controls on the layouts provide opportunities for museum visitors to run the trains and operate activities on the layouts.

The Power of Steam

Want to learn more about steam power? Visit www. and click on the "Roads Scholar" link and then "GPD Toy Train Museum" to learn how to create an experiment that demonstrates the power of steam.

Fuel for Thought

Today most trains run on diesel or electric power, but for many years, they were powered by steam. A Greek inventor named Hero, who lived in Egypt nearly 2000 years ago, first proved that steam could be used to make objects turn. To entertain people, he made a revolving metal ball that held water and was fixed over a fire. When the water inside boiled and turned to steam, it escaped through the jets and the ball spun around. It wasn't until the beginning of the 18th century, however, that steam power began to be used with heavy machinery.

Think Tank

Discussion questions for the whole family to consider:

Some model railroaders look upon their hobby as a sort of time machine that lets them visit a distant time or place through the trains and layouts they create. Trains have figured prominently in history all over the world — from the circus trains of the American West to the Orient Express in Europe. Where and when would you like to go? What would the train be like? How about the buildings and the landscape?

Links index.htm (home page for the GPD Toy Train Museum)

Wheels Are Turning

Parents and caregivers: These activities can help your child meet Arizona's educational standards. Visit www. and click on the "Roads Scholar" link to see the specific standards addressed.

If you were creating a scale layout and wanted to put a house in it — or maybe even yourself — you would have to calculate how large to make your models. Use the formula below to calculate the size of your models for each of the commonly used model train scales.

Scale Distance Ratio 75-foot-long My Height: 30-foot-

between rails locomotive high house

Z scale 6.5 mm 1:220 4 inches

N scale 9 mm 1:160 5 1/2 inches

HO scale 16.5 mm 1:87 10 1/2 inches

S scale 7/8 inch 1:64 14 inches

O scale 1 1/4 inches 1:48 18 3/4 inches

G scale 45 mm 1:22.5 40 inches

Use the following formula to make your conversions:

First, calculate the size of the item being converted into inches. For instance, a 75-foot-long locomotive would be 900 inches (75 x 12 inches in a foot).

Next, divide that number by the number of the ratio for the scale are using. The ratio for Z scale is 1:220, so divide 900 by 220 and you will get 4 (with a remainder of 20). Since the remainder is so small, the answer is rounded to 4 inches.

● "Roads Scholar" is written by Kathleen Williams of Crizmac Art and Cultural Education Materials, a Tucson-based publisher of curriculum used in schools, museums and research programs nationwide.