© Museum of the History of Science, Oxford

These four small wooden objects are an icosahedron (20sided) , a cone, a dodecahedron (12sided), and a cube. They are English and were made in the 17th century. They were owned by the Professor of Geometry at Oxford University. They would have been used by him for teaching students about maths.
Just like pupils now, geometry students in the 17th century had to learn about triangles, squares, parallelograms, circles and curves. This was geometry in two dimensions or what is called 'plane geometry'. They also had to know about threedimensional geometry and to learn about things like tetrahedrons (pyramids), cubes, octahedrons and dodecahedrons.
Geometric solids made out of wood became very popular in the late 17th and in the 18th centuries. They were used for teaching students basic geometry lessons. At this time mathematics was becoming an important subject for people to study at school and at university. In previous times, mathematics had been studied more by scholars and other experts. In the 18th century it was necessary for those who thought they were "gentlemen" to be good at mathematics. It was also fashionable for ladies to study mathematics, and mathematical puzzles were often included in magazines such as the Ladies' Diary, which was a sort of Cosmopolitan magazine of its day.
Over the passage of time a lot of effort has been put into making sure that geometry is taught in an easy to understand and enjoyable way. In the 16th century books on geometry used to contain only boring flat diagrams. But in 1570 a man called Henry Billingsley brought out a geometry book that had popup diagrams showing different geometrical shapes.
In the 17th century almost all geometry was taught using a book called the Elements of Geometry. The Elements of Geometry was written by Euclid. Euclid was an ancient mathematician who was born in about 325 BC and set up a school in Alexandria which is in Egypt. In the Elements of Geometry he wrote down almost everything that was known about geometry at the time.