Final answer:
The student can classify the salad dressing as a heterogeneous mixture based on the observation that the oily component and the vinegar component have separated and that the herbs are visibly distinct in the oil layer.
Step-by-step explanation:
The student can use the simplified model of matter to determine the classification of salad dressing. Based on the observation that the oily component and the vinegar component have separated and that the herbs are visibly distinct in the oil layer, the student can classify the salad dressing as a heterogeneous mixture. A heterogeneous mixture is a mixture with a composition that varies from point to point. In this case, the oil and vinegar separate, and the herbs settle, resulting in visible differences throughout the mixture.