When a learner encounters new information that cannot be readily incorporated…

Piaget described cognitive development as adaptation through two complementary processes acting on mental schemas. Assimilation fits new experience into an existing schema without changing it, while accommodation modifies an existing schema, or builds a new one, when the incoming experience does not fit. Equilibration is the broader self-regulating drive that moves a learner between these two processes to restore a stable, coherent understanding.

The stem describes new information that cannot be readily incorporated into the learner's existing framework, so the learner must adjust their current understanding. This is exactly what happens when a schema itself is changed to make room for information it could not previously hold, which is the definition of accommodation.

Ruling out the other options:

• Assimilation would apply if the new information fit smoothly into the existing framework without any change to it, which is the opposite of the adjustment the stem describes.

• Schema formation names the initial building of a mental structure, not the response when an established structure conflicts with new experience.

• Equilibration names the overall, ongoing balance-seeking process across many assimilation-and-accommodation cycles, not the single act of reshaping one schema described here.

Because the existing schema itself is altered to hold information it could not otherwise accept, accommodation is the process at play.