Kid President - How To Change The World with Kindness. Teaching kindness to children is part of the fourth National Health Education Standards: Students will demonstrate the ability to use interpersonal communications skills to enhance health and avoid or reduce health risks. Learning to be kind helps build a positive learning environment.
The stone-throwers took two forms-either like the arrow-firing apparatus or large one-armed catapults, known in the 4th century CE as the onager or 'Wild Ass' because of its terrific recoil but, in fact, first appearing in the 2nd century CE.
Report Abuse. The origins of the abacus are disputed; many cultures are known to have used similar tools. It is known to have first existed in Mesopotamia[1][2] and China,[3] and was invented sometime between 1000 BC and 500 BC.[4] The first abacus was almost certainly based on a flat stone covered with sand or dust.