Children's natural inquisitiveness makes them natural-born scientists. Dorothy Steane discusses ways to embrace this curiosity, incorporate it into the curriculum, make science learning fun and lead children towards discovering answers to science questions for themselves.

Throughout history, humans have felt the need to explain the world around them. Different cultures and belief systems have legends and stories to explain the appearance of life on this planet. In today's technological society such stories are, for many people, not as acceptable as they may once have been. Questioning minds search for better, more plausible explanations for the hows and whys of the natural and technological world. The study of science in school can help children make sense of the world around them, develop informed opinions about how and why they should manage their environment, their health, and the many other issues that confront them as they mature. It can also provide alternatives to the legends and myths surrounding how the earth came to be, and how life began on earth. The degree to which a student wishes to understand the world around them will influence which branches of science capture their interest.

In Tasmania, the Education Department has adopted a curriculum of 'Essential Learnings', based on projects. Rather than learning the fundamentals of a subject and applying them to real-life examples later on, they take real-life examples and study all aspects of them (history, science, creative writing, mathematics, etc). One aspect of the Essential Learnings philosophy is that children are encouraged to ask questions, discover things for themselves and undertake research. Let's examine how the relatively simple concept of a terrarium may lead to classroom discussions of many branches of science.

First of all, what is a terrarium?
There are many different types of terraria, but generally they consist of plants grown in a watertight container. More complex setups can include ponds with animals such as frogs and insects, though maintaining one of these systems in a sealed environment requires very careful EDUCATIONAL balancing. Terraria need not be complex to capture a child's imagination. Worm farms or ant farms in glass containers are forms of terraria that provide children with weeks of amusement.

Let's take a hypothetical terrarium in which we have placed a pond, some rocks and earth planted with moss, ferns and other small green plants. In the pond we have placed some frog spawn, and a little bit of algae collected from a local dam or pond. We then seal up the terrarium, making it both airtight and watertight, and put it near a well-lit window. What can children learn from this miniature ecosystem?

The terrarium is a dynamic system, and as time goes by children can watch, wonder, ask questions and find answers. For the first couple of days there may not be much change in the terrarium. The first thing to happen will be water condensing on the glass. Why? Water evaporates from the pond, the soil and from the plants themselves. The water condenses on the glass because the glass is cold, which causes the water 'gas' to become liquid again. This phenomenon can initiate a discussion about water cycling in nature, rain and other weather patterns, or a discussion about the chemistry and physics of water. For example, what are the three states of chemicals (solid, liquid, gas)? How does water evaporate? How does it condense? How do clouds form? Do other chemicals evaporate and condense?

The water on the glass could also lead to a discussion about plant and animal respiration (ie using energy and breathing). Just as humans use energy to grow, so do plants. Just as humans lose water when they breathe out, plants lose water through their stomata (the holes in the leaves through which they 'breathe'). Some plants are better at conserving water than other plants–put a fern and a cactus side by side on a window sill without any watering, and see which lasts longer. Why does one fare better than the other? Are some animals better at surviving drought than others? Hence begins an investigation into how and why plants and animals need water and air.

As time passes, black spots start to grow and move in the frog spawn. Eventually tadpoles hatch and swim about in the water. Children love tadpoles, and get very excited as they grow legs, lose their tails and come out onto the land. Watching the growth and development of these animals will no doubt lead to a discussion of hormones and life cycles, not just of frogs, but of other animals—comparative biology in action! In a perfect terrarium there will be sufficient food for the frogs (insects) and tadpoles (algae).

As more time passes, the damp rocks will begin to grow moss. We may see fungi growing on or in the soil. How did the moss and fungi get there? What do fungi live on? Why aren't fungi green? Are they plants? Why doesn't the moss need soil? Why do other plants need soil? What is in soil? Where does soil come from? Now we go from biology to geology (rocks and minerals), physics (erosion) and chemistry (minerals and other soil chemicals) and then back to plant nutrition. Yes, plants need good nutrition, just like people do.

In our 'perfect' terrarium we never need to add water, nor do we need to provide fresh air for the plants and animals. We've already learnt why we don't need to add water. But where do the animals get their oxygen? Surely it would all get used up after a while? Here begins an exploration of the delicate balance of plants and animals in nature; why animals need plants not just for food, but for the air they breathe. The more physics-oriented students might also be interested in the concept of the 'conservation of matter'.

All aspects of biology and geology have their foundations in chemistry and physics. Generally, biology and geology are more appealing to younger children because they can relate the things they learn directly to the world around them, and you can often 'see' biology (and to a lesser extent, geology) in action. However, as children mature they are able to grasp increasingly complex concepts of chemistry and physics, and those that are interested will explore these fields further. The most important thing about teaching science to anyone (not just kids!) is to make it fun and exciting, so that they want to learn more.

If you are interested in making a terrarium in your classroom, there are numerous Internet sites to get you started. Do a Google search of 'terrarium' or visit the following sites: www.uen.org/Lessonplan/ preview.cgi?LPid=618 www.kernsite.com/uwp/modules/watercycle/hylab.htm

If you would like to raise tadpoles, there are also numerous sites to help you with water quality and ideas for food (such as http://frogs.org.au/arc/index.html), as well as other fun activities relating to frogs. Because many species of frog and toad are protected, you should check with your State government to find out whether you need a license to collect frogs, tadpoles or frog spawn. Links to relevant sites for Victoria and Tasmania can be found at http://frogs.org.au/arc/legal.html.

Dorothy Steane is a research fellow with the School of Plant Science at the University of Tasmania.

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