A teacher begins the class by demonstrating the chemical test of starch in a…

Bloom's Revised Taxonomy (Anderson & Krathwohl, 2001) organises cognitive processes into six levels — Remember, Understand, Apply, Analyse, Evaluate, and Create. "Applying" is defined as carrying out or using an already-learned procedure, method, or piece of information in a given or new situation — for example, executing, demonstrating, implementing, or using a technique.

In the given scenario, the teacher demonstrates the chemical test for starch — that is, performing an already-learned laboratory procedure (adding the reagent to the food sample and observing the result) in a specific classroom context. Carrying out a known method in a practical context is exactly what this cognitive process involves.

• Creating combines elements into a new, original pattern or product (for example, designing a fresh experimental method); performing a standard, already-established test does not involve producing anything new.

• Analysing breaks material or a process into its constituent parts to examine how they relate to one another (for example, comparing results across different samples); simply carrying out a known procedure does not involve breaking it into parts.

• Understanding involves constructing meaning from instructional material — interpreting, explaining, or summarising an idea; physically carrying out a procedure goes beyond merely grasping its meaning.

Since the teacher is executing an already-learned procedure in a specific practical context, the cognitive process demonstrated by the underlined word is Applying.