Sunspeed device shows that shadow should advance trigonometrically with constant angular speed passing a new ring each 10 minutes and the rising shadow should remain aligned to the linear grove once set. The initial position has to be the one without the shadow at all. The device has to prove or disprove astronomical global model of Earth in every single classroom in the world!
This didactical toy shows constant rotation of Earth proving that it is cause of Sun's apparent movement.
Sunspeed's design is created by Andrija Radović, http://www.andrijar.com All inquiries should be sent to firstname.lastname@example.org