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What is a rabbi? Judaism – Religion

By |2018-09-10T09:58:12+00:00August 24th, 2017|Religion, West Asia|

The rabbi Maimonides, in a later medieval painting What does "rabbi" mean? Rabbi means "great one" in Hebrew, or "respected one". It's a Hebrew word related to the Arabic word rabb, meaning "lord." Saying "Rabbi" showed respect, like calling someone "Sir". More about the Hebrew language When did the word "rabbi" get started? In [...]

What is baptism? – History of Christianity

By |2018-04-24T15:45:39+00:00August 21st, 2017|History, Religion, Romans|

Torchlight parade (this one is actually in India) Even before the time of Jesus, many mystery religions of the ancient Mediterranean had some sort of ceremony that people had to do in order to join the cult. Some of these, like the Eleusinian mysteries, involved dipping yourself in water to wash away your past life, and to show that [...]

What is work? Physics definitions

By |2018-05-31T11:49:15+00:00August 17th, 2017|Physics|

Ancient Egyptian cattle plowing (Louvre Museum, Paris) You might think you know what work is, like homework, or having to pick up your room, right? But to scientists, work has a more definite meaning: work is force x distance. That means that you can measure work by measuring how much force, or energy, [...]

What is feudalism? Definition of medieval feudalism

By |2018-04-27T09:18:11+00:00August 1st, 2017|Government, Medieval|

Medieval feudalism: Harold swears an oath to William (Bayeux Tapestry, about 1077 AD) What is feudalism? Feudalism is a way to govern a large state when the king is poor and not very powerful, and when there aren't good roads so it is hard to communicate with people who live far away at the other end of [...]

What is area? Simple geometry

By |2017-07-29T13:29:39+00:00July 29th, 2017|Math|

Calculating the area of your room. The area of a room is the size of the floor. Suppose you wanted to find out whether your room was really bigger than your brother's room. You'll need to measure your room, and his room. Suppose your room is ten feet long and fifteen feet wide, [...]

What is a rhombus? Simple geometry

By |2018-04-23T16:01:48+00:00July 29th, 2017|Math|

This is a rhombus, divided so you can figure out the area. A rhombus is a kind of quadrilateral that has two sides that are parallel to each other, and another two sides that are parallel to each other. A rhombus is a special kind of parallelogram, and squares and rectangles are special kinds of rhombus. To figure out the perimeter of the rhombus, you [...]

Rectangle – area and perimeter

By |2018-04-23T16:01:22+00:00July 29th, 2017|Math|

This is a rectangle. A rectangle is a flat shape, in one plane. It's defined by four points at the four corners. A rectangle has two sides of equal length opposite each other, and two other sides of equal length opposite each other, and four corners, all right angles (90 degree angles). A square is a special kind of rectangle. [...]

What is a pyramid? Square pyramids

By |2017-07-29T11:57:36+00:00July 29th, 2017|Math|

A pyramid with a square base. A pyramid is a three-dimensional solid form made out of triangles. Some pyramids also use a square. There are two common kinds of pyramids: triangular pyramids that you make by fitting four triangles together, and square pyramids that you make by fitting four triangles together on a square base, like the [...]