o_s.pptx | |
File Size: | 3201 kb |
File Type: | pptx |
this one is a prezi presentation of different kinds of eletricity generator
this one is a prezi presentation of how does human count time from ancient to future
http://en.wikipedia.org/wiki/History_of_timekeeping_devices
http://en.wikipedia.org/wiki/History_of_timekeeping_devices