I learned about four inventions this week and they are chess, the arquebus, the printing press, and the mainspring. The first invention I learned about this week is chess. Chess teaches military strategy and math skills. In the 1700s, it became seen as a tool of self improvement. The second invention I learned about this week is the arquebus. Through time, its accuracy improved very much. It led to more refined firearms and strategies. The third invention I learned about this week is the printing press. Books could now be printed faster and cheaper. It could print 3,600 pages a day. Europe printed millions of books. The last invention I learned about this week is the mainspring. It tempered steel tightly wound into a coil. The mainspring made portable clocks possible.