By Airavati Subramonia

Under the guidance of Tafheem Masudi and Sukant Khurana

Space science is a wonderful subject to teach but often characterised as hard. It is a subject that has evolved constantly and by adopting new practices it can be taught in a more engaging way. Children are inherently inquisitive and even very young students can grasp the basic concepts of astronomy if taught in the right manner. One of the ways in which the teaching of space science can be made more intriguing and less confusing is by adopting the strategy of providing a contextual framework.

The premise behind this strategy is that we cannot expect students to absorb scientific facts without having a context in which to place them. So we have to provide them with a mental edifice, often called a contextual framework, within which they can organize the astronomical concepts and facts that we want them to learn. For example, the number of stars in the observable universe is 10²².This concept cannot be easily comprehended by young children. To give meaning to this number and helping students to develop a contextual framework for the enormity of the universe we can provide an analogy by comparing the number of stars to the number of grains of sand on all the beaches on earth.

This layout is especially necessary when teaching about the basic hierarchy of structure in the universe. Students often confuse the term solar system and galaxy using them interchangeably. This is because the pictures of solar system and galaxies are about the same size when printed in a book or when projected on a screen.

So it becomes difficult for students to comprehend that they differ in size by more than a dozen orders of magnitude. This can be solved using a suitable analogy from real life which brings sizes into perspective. Teachers often use the sports ball analogy for giving an idea of planet sizes. Relating the earth to a tennis ball, the sun to a basketball, mercury to a golf ball and so on helps students distinguish the relative sizes of planets. Similar models can be used to teach the perspective of distances of planets from the sun.

A hard topic to teach as well as comprehend is the fact that the universe is expanding- in the sense that galaxies are moving farther apart which implies that everything was close together at some point of time in the past. A suitable method that could be employed to explain this concept would be the raisin bread analogy, which explains aptly the expansion of the universe where each raisin represents a galaxy cluster. As the dough rises and expands, the raisins on the surface of the bread tend to move apart. This is similar to what happens in the universe; as it expands constantly, the galaxies move further away from each other.

As we move to higher levels it is important to present a sense of the scale of space and time in a proper perspective. The popular ‘powers of ten’ approach merely gives them numerical relationships and only works well for students who are strong in order of magnitude. For the scale of space with reference to the solar system and beyond, the students can be shown related videos using smart boards. For the time model, we can use the Carl Sagan’s device of the Cosmic Calendar in which we imagine the history of the universe from the Big Bang to the present compressed into a single year.

The cosmic calendar as imagined Carl Sagan.

Images have always been central to the craft of space science teaching and now we have access to smart board software, power point presentations, audio files and even fully worked-up teaching packages that are readily available to teachers. This enhances learning and can be used for explaining the dynamics of the universe — earth’s rotation on its axis, revolution around the sun, orbiting the galactic centre, and its movement relative to distant galaxies because of universal expansion. The seasons on earth, the phases of the moon and the daily motion of the stars can also be better explained using classroom computers.

Space science has always been fascinating and has become more so with access to such exciting and powerful learning tools. However, there is no single successful method for teaching. Every teacher has a unique style of imparting knowledge and every student has a unique style of learning. Simply put, good teaching is hard work and requires adapting to students’ needs and being willing to try different strategies in order to find the best fit.

Reference: Jeffery Bennett: Strategies for Teaching Astronomy