Ancient Greek Science
Eclipse of the sun
Greek people were very interested in science as a way of organizing the world and making order out of chaos, and having power over some very powerful things like oceans and weather. From about 600 BC, a lot of rich, educated Greek men spent time observing the planets and the sun and trying to figure out how astronomy worked. They got their first lessons from the Babylonians, who were very good at astronomy and also very interested in it.
By the 400s BC, Pythagoras was interested in finding the patterns and rules in mathematics and music, and invented the idea of a mathematical proof. Although Greek women usually were not allowed to study science, Pythagoras did have some women among his students.
Beginning around 450 BC, about the same time as Pythagoras, Hippocrates and other Greek doctors wrote medical texts. Greek doctors tried to figure out a scientific theory that explained diseases. They thought if you were sick you had too much or too little of four basic substances: blood, black bile, yellow bile, or phlegm (boogers). That wasn't right, but it sounded scientific. Doctors in India and China had similar ideas, but maybe a little later.
Socrates, a little bit later, developed logical methods for deciding whether something was true or not. In the 300s BC, Aristotle and other philosophers at the Lyceum and the Academy in Athens worked on observing plants and animals, and organizing the different kinds of plants and animals into types. Aristotle's work was yet another way of creating order out of chaos.
Learn by doing: find ten plants outside and try to divide them by type.
More about Greek astronomy
Greek and Roman Science, by Don Nardo (1998). Nardo has written a lot of good books about the ancient world for kids; this one is no exception.
Ancient Science: 40 Time-Traveling, World-Exploring, History-Making Activities , by Jim Wiese (2003). Activities, as the title says - how to make your own sundial, and so on. The author is a science teacher.
Greek Science After Aristotle, by G. E. R. Lloyd (1975).