In unit one, an instructor is explaining what the Tropic of Cancer is.
A person uses a whiteboard to show how to calculate latitude.
A person is using a special pen to write on a special screen.
A woman is talking  while pointing at a whiteboard with an arc and degrees on it.
A WOMAN USING A WHITE BOARD, ILLUSTRATES DIFFERENT CONSTELLATIONS TO EXPLAIN LATITUDE.
Someone is calculating the latitude of the Tropic of Cancer and the equator.
A person explains how to calculate latitude by drawing it on a board with marker.
A person writes some text and shapes on a white board while he explains the topic
A man is teaching euclidean geometry and drawing diagrams on a whiteboard
A person providing instructions in how to calculate certain latitudes given two locations.