Rocks
There are 3 types of rocks: igneous, sedimentary, and metamorphic. Identifying Basalt Identifying Conglomerate Identifying Marble
Posts
The 5 Mechanical Stress Types
There are 5 different mechanical stress types. It is important to know them, so the buildings we make do not collapse, but also we use materials rationally, without unnecessary expenses. For example, in a pillar, it is important to reinforce the sides, not the centre.
History Map
Choose a year up to 3 000 BC, and see the borders of the past on a world map! How many countries where there in modern day Italy at 1700 AD? What about India at 1000 AD? How did Antient Egypt change over 1000-1500 BC? http://geacron.com/home-en/