Exercise 3: sample answer

Your results will depend on the date and your latitude, but the pattern should be the same everywhere. Around midday the shadow is at its shortest, and it points roughly north in the Northern Hemisphere (the Sun is then due south, around 13:00 British Summer Time in Edinburgh, a little later than the clock says because of the clock's offset from solar time; check the exact time for your date). In the morning the shadow is long and points westward; in the afternoon it is long again and points eastward.

Example write-up: "At 10:00 the shadow was long and pointed to the north-west. At 12:00 it was shortest. At 14:00 it was long again and pointed north-east. The Sun's changing height changes the length and its changing direction swings the shadow around, which is exactly what a sundial uses."

If you used a stick in the ground, mark each shadow tip with a pebble. The three marks form a shallow curve, and that curve is the basis of the sundial.