## Packages

From the geometry of Euclid to the shape of the Universe — geometry is a vast field. We've got plenty of articles exploring geometry from all angles, so have a look and take your pick.
So basic, yet so tricky: prime numbers are the atoms among natural numbers and lie at the centre of some of the most difficult open problems in maths. This package brings together all material we have on primes, from prime number algorithms to new discoveries. And you will find out what all that's got to do with David Beckham.
This issue's teacher package brings together all Plus articles on group theory, exploring its applications and recent breakthroughs, and giving explicit definitions and examples of groups. It also has some handy links to related problems on our sister site NRICH.
This issue's teacher package brings together all Plus articles on vectors and matrices, exploring anything from the maths of computer movies to climate change. It also has some handy links to related problems on our sister site NRICH.
This issue's teacher package brings together all Plus articles on probability and statistics, exploring anything from maths in the dock to games of chance. It also has some handy links to related problems on our sister site NRICH.
Complex numbers — what are they, how do they work and what do they have to do with computer-generated movies, fractals and chaos? This teacher package brings together all Plus articles on complex numbers and gives some handy links to related problems on our sister site NRICH.
The flocking behaviour of birds, the spread of diseases and the Cuban missile crisis — all of these and much more can be modelled mathematically. In our second teacher package we bring together all Plus articles on mathematical modelling, ready for use in classroom discussions or students projects.
One thing that will never change is the fact that the world is constantly changing, and differential equations are the way we mathematically describe the changing world around us. In our first Teacher package we bring together all the material on Plus that deals with differential equations, including applications in biology, physics, finance, and even football!