This video shows how Nicolaus Copernicus, an early astronomer, scientist and priest in Poland, thought the sun was at the centre of the solar system. This theory was known as the heliocentric model. It was controversial, as accepted wisdom at the time (supported by the church) was that Earth was at the centre of the universe. In this video, he compares his ideas with those of Aristotle and Ptolemy, who believed the celestial model of Earth at the centre of the solar system, with the sun and other planets in its orbit. Teacher notes: As a starter to introduce a practical science activity, you could write a simple quiz to encourage students to capture the keywords shown in the video. Students can write their own definitions from these words using the internet or science dictionaries to improve their scientific vocabularies. To consolidate their knowledge, you could get students to make booklets that include key information about the work of Nicolaus Copernicus. They could define the keywords featured in the video and find five or more additional pieces of information about the work of the scientist using books, encyclopedias or the internet.