Introduction to sundials

Introduction to sundials

Pencil and paper
Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
This task is exploring how sundials can be used to tell the time.
sundial
If you stand outside on a sunny day you can see your shadow. If you stayed in one place all day long, you would see you shadow moving. You could put a stick in the ground and make marks where the stick's shadow was every hour. Now you can can tell the time by looking at where the shadow falls on your marks.
Shadow sticks have been used by humans to tell time for many thousands of years. Another name for a shadow stick is a gnomon (no-mon). The ancient Egyptians built tall gnomons made from stone, which they called obelisks. People could tell the time by looking at the where the obelisk's shadow fell. Later the Greeks and Romans developed sundials to tell the time. Sundials are smaller and work better.
 
a) To make your own sundial:

  • Write N, S, E, and W on your plate.
  • Put some Blu-tack in the middle of the plate.
  • Place a small stick straight up in the Blu-tack.
  • Put your sundial in a sunny and safe spot.
  • Make sure "S" on your sundial points South. (Your teacher will show you South).
North East South West marked on a plate
b)
At 10:00 a.m., 12:00 p.m., and 2:00 p.m., carefully draw around the whole length of the shadow and write the time next to it.
 
c) i)
Write down what you noticed about the size of the shadow your sundial made.
 
 
 
 
 
 
  ii)
Write down what you noticed about how the shadow moved.
 
 
 
 
 
 
 
 
d)
Draw and label on your sundial where you think the Sun's shadow will fall at the following times:
  • 11:00 a.m. and
  • 3:00 p.m. 
Write the time next to both shadows.
 
e)
Draw where the Sun would be in the picture below to make the shadow shown.
 
 
 
f) i)
In which sort of day would the sundial not tell the time very well? 
(Circle as many as you think.)  
 
Cloudy        Bright and sunny        Rainy        Clear blue skies  
 
  ii) Explain why.

 
 
 
 
 
 
 
 
Task administration: 
This task can be completed with pencil and paper and only.
 
Equipment:
Large paper or plastic plate; permanent marker; Blu-tack; small kebab stick or toothpick (3-4 cm high); compass.
  • Shadows will need to be recorded during the day (the 11:00 p.m. and 3:00 p.m. predictions can be checked the next day).
  • N, S, E, W, needs to be on the plates to help orient the sundial.
  • You may like to read an "Introduction to Sundials" to the students prior to the activity.
  • This practical requires sufficient sun for the sundials to work.
  • Students will need to use a permanent marker to draw around the whole length of the shadow.
  • Discuss the idea of a good location to put a sundial – somewhere sunny and safe from being moved.
  • Mark out South for the children to point their sundials.
  • For supplementary reading on sundials and how they work try: http://www.sundials.co.uk
Copyright: 
Images: NZCER
Level:
2
Curriculum info: 
Science, Investigating in science, Planet Earth
Keywords: 
astronomical systems, sundials, shadows, Sun, south pole, compass, direction
Description of task: 
For this practical task students create a sundial by marking observations and recording the time for each hour, and answer questions about shadows and sundials.
Science capabilities: 
Gather and interpret data
Answers/responses: 
a)   Makes the sundial with N, S, E, and W marked correctly.
b)   Traces evenly spread shadows (25°-35° apart) 10:00 a.m., 12:00 p.m., and 2:00 p.m.
Shadows are longer at 10:00 a.m. and 2:00 p.m., and shorter at 12:00 p.m.
c) i)
 
ii)

The shadow is shorter in the middle/some shadows are longer.
NOTE: Do not accept statements only recognising the shadow
getting longer or shorter.
The shadow moves anti-clockwise/West to East/moves left to right.
d)   Marks 11:00 p.m. shadow approximately half way between 10:00 a.m. and 12:00 p.m.
Marks 3:00 p.m. shadow approximately 10°-20° after 2:00 p.m. (anti-clockwise).
e)  

f) i)
ii)		 Cloudy and Rainy circled.
The shadow is hard to see/not as clear/at night time/when it's dark/when there is no sunlight.