What piece of equipment will help students improve kick mechanics while in streamline body position?

The correct choice, which is fins, is an effective tool for enhancing kick mechanics while swimmers maintain a streamlined body position. Fins provide additional propulsion and resistance in the water, allowing students to focus on optimizing their kicking technique without the challenge of balancing or generating speed solely with their legs.

When using fins, students can also more easily feel the correct movement patterns required for an efficient kick, as the fins amplify the feedback from the water. This helps them develop muscle memory for effective kick mechanics that they can carry over to swimming without fins. Moreover, fins encourage a proper kick from the hips rather than the knees, reinforcing the streamlined position and enhancing overall body alignment in the water.

Using fins in a streamlined position also allows instructors to assess and correct students' kick form with greater precision, making them an ideal choice for this type of training. Other equipment options, while beneficial in different contexts, do not specifically focus on improving kick mechanics in the same effective manner as fins do.