12-18 years

Telescope in the pocket

困难: ★

Making your own sky disk

困难: ★

Form the armillary sphere to the astrolabe

困难: ★

The pyrenean shepherd’s dials

困难: ★

Building simple sundials

困难: ★

Latitude Gnomon and Guadrant for the Whole Year

困难: ★

Making helioscopes with four sticks

困难: ★