The Programme for International Student Assessment (PISA) is like a really big test that kids take all over the world to see how well they understand certain subjects like reading, math, and science. The test happens every three years, which means it has happened in the years 2000, 2003, 2006, 2009, and 2012.
During the test, kids are asked lots of questions about things they've learned in school. They also do some problem-solving tasks and answer questions about themselves and their life outside of school. All of the answers that the kids give are collected and analyzed to see how well they did compared to other kids in their own country and other countries around the world.
PISA helps people like parents, teachers, and leaders in government understand how well kids in their country are doing in school compared to kids in other countries. It can also show what subjects kids in different countries might need more help with, like if lots of kids are struggling with science.
The information from PISA is really important because it helps people make decisions about how to make schools better, like what teachers should be teaching or how they should teach it. It also helps people see what countries have the best education systems in the world.