The generation effect is the phenomenon of being better able to remember information that has been generated within the mind rather than material that had been read or heard. This phenomenon is not well-understood and there are a few theories that attempt to explain it. The generation effect is possibly due to the effort that is involved in the attempt to figure out a problem rather than the passive effect of merely reading about it. This is also possibly the source of success in the 'hands-on' learning that is used in some classrooms and subjects.
A common example of this is the use of manipulatives and problems that require critical thinking in teaching and learning math as opposed to learning only to memorize addition/subtraction/multiplication/division tables.