A few days prior to carrying out this activity the teacher should ask the students to observe the shadows cast by them at different times of the day when walking to and from school, when playing outdoors etc They will quickly register that shadows are long when the sun is low and short when it is high. Now ask them to select a pole. a tree or any other object which it is possible to observe at frequent intervals throughout the day. Let them mark the length and the direction of the shadow before the first period of the day, and again after every period. Any one student at a time can go out and do this so that the schedule of classes is not disrupted. At the end of the day take out the whole class to see the result of the day’s work. At the end of each shadow mark you may put down the time at which that reading was taken, i.e. the time at which each period began or ended. Now ask the students:
· What was the time when the shadow was the longest?
· At what time was the shadow shortest?
· What time was noon? The students may repeat this activity over the next two or three days to find out if the positions and the lengths of the shadows vary at the given points in time.
VARIATION / EXTENSION
By doing this exercise four times in the year, i.e. on or around the 23rd of March, June, September, and December, the students can begin to understand how the apparent track of the sun across the sky varies around the year. Let the students build their own sun-dial by driving a stick into the ground and marking its shadows by the hour. This can be used for three to four weeks to tell the time. After that correction factors will have to be