♦ Find out from your grand-parents or other elders –
(a) how did they go to school?
(b) how did they get water for their daily needs when they were young?
(c) what means of entertainment did they use?
♦ Compare the above answers with how you do these tasks now.
♦ Is there a difference? If yes, in which case more energy from external sources is consumed?
♦ Take two conical flasks and paint one white and the other black. Fill both with water.
♦ Place the conical flasks in direct sunlight for half an hour to one hour.
♦ Touch the conical flasks. Which one is hotter? You could also measure the temperature of the water in the two conical flasks with a thermometer.
♦ Can you think of ways in which this finding could be used in your daily life?
♦Study the structure and working of a solar cooker and/or a solar water-heater, particularly with regard to how it is insulated and maximum heat absorption is ensured.
♦ Design and build a solar cooker or water-heater using low-cost material available and check what temperatures are achieved in your system.
♦ Discuss what would be the advantages and limitations of using the solar cooker or water-heater.
♦ Discuss in class the question of what is the ultimate source of energy for bio-mass, wind and ocean thermal energy.
♦ Is geothermal energy and nuclear energy different in this respect?
♦ Where would you place hydro electricity and wave energy?
♦ Gather information about various energy sources and how each one affects the environment.
♦ Debate the merits and demerits of each source and select the best source of energy on this basis.
♦ Debate the following two issues in class.
(a) The estimated coal reserves are said to be enough to last us for another two hundred years. Do you think we need to worry about coal getting depleted in this case? Why or why not?
(b) It is estimated that the Sun will last for another five billion years. Do we have to worry about solar energy getting exhausted? Why or why not?
♦ On the basis of the debate, decide which energy sources can be considered (i) exhaustible, (ii) inexhaustible, (iii) renewable and (iv) non-renewable. Give your reasons for each choice.