How to make a simple watch by yourself?

The simple criteria for primary school science are as follows:

1, prepare a plastic board.

2. Then print the clock.

3. Cut the clock according to the contour.

4. Stick the clock on the bottom of the plate with Tauren glue.

5. Then prepare a pencil.

6. Insert the pencil in the center of the clock.

7. Put your watch in a sunny place.

8. As the sun moves, the shadow of the pencil moves on the watch and indicates the time.

Brief introduction of guibiao

Ghost table is an astronomical instrument for measuring the length of the sun shadow, which consists of two parts: ghost table and ghost table. Like the sundial, the sundial is an ancient astronomical instrument, which uses the shadow of the sun to measure. The so-called altimeter method, popularly speaking, is to erect a pole perpendicular to the ground and determine the seasonal change by observing and recording the change of its shadow at noon.

A straight rod perpendicular to the ground is called a "table", and a scale horizontally placed on the ground and engraved with scales to measure the shadow length is called a "GUI". It can be used not only to make festivals, but also to list the dates of the future solar calendar year and the twenty-four solar terms in the almanac, which is an important basis for guiding the agricultural activities of the working people of the Han nationality.

Mark the length of the shadow on a circle with a period of one year. The center of the circle is the standing point of the table, and the generated map is a Taiji diagram with a non-zero center. After eliminating the center point of zero radius, the Tai Chi map is the common 24 solar terms Tai Chi map.