What's the time Mr Sun?
The Basic Idea
A pole or long stick is used to create a shadow to allow you to build a huge sun dial. The children create markings for the hours/minutes (1/4 hours etc) of the clock to be used and strips of paper to join these to the pole on the ground. A sunny day in Winter is best! Markers could be 'pegged in' on a field, or chalk marks could be used on a playground.
In more detail...
Discuss how we tell the time today. What would have been used and how would these instruments have been used, 10 years ago, 50 years ago, 100 years ago, 1000 years ago...
This website}for-time.com/timeline.htm) has a useful timeline.
Look at examples of small sun dials- link this to angle work and discuss how accurate these would be.
How could these be made more accurate? More easy to tell the time.
(Position the large pole into the middle of an area big enough for the task and where it will not be moved all day. Test in advance just before and after school to see how long the shadows will be.)
Plan out in class how you will measure the shadow and how you will mark this. Suggestion is that in class you then make: -Markers for the hours will need to be made (9am- 3pm) -Strips of card (an inch or two thick) joined together to join the arrow markers to the pole.
Once this has been created, go out with the class and discuss the best way to mark the shadow on the field. Model with one strip of card and hour marker. Use the tent pegs to secure these to the ground!
In small groups, and on the following day, get the children to go outside and mark off the hours at set times. This could be every half hour or every hour- up to you and the group.
Once this has been created, you can then check the following day to tell the time.
** Alternatively, children could make their own using metre sticks **
How to take it even further or make it more challenging
Use the angles between hours, the lengths of the shadows to take the challenge further. Work when the sun is in the 'middle' of the sky. Work out the three hours before midday and then use angle work to predict and mark out when the three hours after midday will be. Plot the angles of the hours into a spreadsheet and calculate using this to find the time to the nearest degree! Why are sundials tilted? Use material to make a large triangle to hang from the pole- why would this help measure the time?