This advice is good as far as it goes but if the class repeats the experiment with a vertical gnomon six months later they will find that the hour lines are very much different. Will this destroy their trust in science? I hope not and their teachers will use this as an opportunity to introduce another topic, the sun and seasonal change. The ancients building megaliths etc learned a lot about their world by observing the sun. Unfortunately a lot of fires were burned and virgins sacrificed to get the sun to come back. The important thing for teachers today is to get the kids to keep asking why and not to take things on faith from all knowing teachers.
A little quiz is appropriate here. Calculate the time for the sun to be at a azimuth of 45º for the summer and winter solstices for a given latitude, say 50º. The difference is remarkable. I found solving this particular solution of spherical trigonometry somewhat more difficult than the usual solutions where the time is known and altitude and azimuth are calculated. Regards, Roger Bailey ----- Original Message ----- From: "Frank King" <[EMAIL PROTECTED]> To: "Sundial Mailing List" <sundial@uni-koeln.de> Sent: Wednesday, July 11, 2007 12:38 AM Subject: Re: Help Oscar! > Dear All, > > I have read the correspondence about Oscar with > much interest. "How," it is almost asked, "can > we used sundials as a means of interesting > children in science?" > > Like Tony Moss, and no doubt several others on > this list, I have given many talks on Sundials > in schools and to brownies and cubs and so on. > > I have minimal knowledge of child psychology > or educational theory (topics which have a > tendency to raise my blood pressure) but I > have made a number of observations... > > Clearly the age of the group will dictate what > you can hope to get across. You won't get very > far unless: > > 1. The children can tell the time from an > ordinary 12-hour two-hand clock or watch. > > 2. The children have some understanding of > North, South, East and West. > > In my experience, many children can tell the time > before they go to school (by which I mean age 5). > Moreover, they have little difficulty adjusting > to the idea of a clock with one hand or to the > idea of a 24-hour clock. If you want to talk about > sundials, this is good news! > > The bad news is that understanding North, South, > East and West seems MUCH harder. > > In my experience, most adults are fairly hopeless > at directions. I have, many times, said I will > meet someone at the WEST door of a particular > Church and I found that the failure rate was high. > I gave up this approach when I found that even the > Vicar didn't get it right! > > For young children (6 to 10) the niceties of a > polar-orientated gnomon can be left on one side. > What they want is something real. Here are a > couple of ideas for teachers... > > Idea one: find some convenient vertical pole > which has a hard surface round it. This might > be a netball post on the playground. > > If the sun is cooperative, you ask the children > outside when they first arrive in the morning. > You note the direction of the shadow and get one > of the children to draw a short length of time > line and mark the time in some way. If there is > a school clock in sight that would be ideal. > > You don't make a great fuss of this but you take > them out again at break time and at lunch time and > at going home time. > > This will get across several things. Notably that > the shadow goes round and that in the course of a > school day it goes round less than half a circle. > > You can ask several questions. Will it keep going > round during the night? Will it still work tomorrow? > Will it still work at Christmas? Will it work when > the clocks go back? > > Idea two: once idea one has sunk in, you can set up > an experiment in the class room. All you need is a > large sheet of paper, a vertical spike and a bright > light. > > You can then simulate the pole and the playground > and explain what is going on. If you lay all this > out on a circular table you can simulate sunrise > and sunset and so on by diving under the table > at night! > > Of course you must let the children have a go > themselves. They must play at being the sun! > You can even write E and S and W on the paper > as well as times. > > I frequently do this in lectures when I use a > 300W lamp and I can wander around simulating a > winter day or a summer day and so on. > > A 300W lamp is a bit dangerous for children but, > on a small scale, a suitable torch would do. > > Enough! > > Frank King > Cambridge, U.K. > > --------------------------------------------------- > https://lists.uni-koeln.de/mailman/listinfo/sundial > > --------------------------------------------------- https://lists.uni-koeln.de/mailman/listinfo/sundial
