Fluid and crystallised intelligence
Fluid ability is reasoning with novel material under time pressure. Crystallised ability is what you have learned and can retrieve. Most papers measure a blend.
Fluid items
Matrix patterns, number series, spatial rotation and digit span. They lean on holding information in mind and finding a rule, with little advantage from prior knowledge.
Crystallised items
Verbal analogies and much arithmetic reasoning. Vocabulary and taught procedure help, which is exactly why those item types are sensitive to schooling.
Why a mix is used
A purely fluid paper is harsh on anyone unpractised with abstract formats; a purely crystallised paper measures schooling. Eight families spread the risk across both.
Scored against age, education and area norms. Free certificate with a QR code anyone can verify.
Questions people ask
Which type declines with age?
Fluid ability declines earlier; crystallised knowledge holds or grows for decades.
Can fluid ability be trained?
Practice improves test performance. Whether the underlying ability moves is still contested.