An ecological instrument used to measure wind direction is?

Step 1: Analyze the question The question asks for the instrument that measures wind direction, not wind speed. That difference decides the answer.

Step 2: Review the instruments

• Secchi disc: a black-and-white disc lowered into water to measure turbidity (how clear the water is) and light penetration. It has nothing to do with wind.
• Wind vane: a pivoting pointer, often shaped like an arrow or a cock, that swings to point in the direction the wind is blowing from. It measures wind direction.
• Anemometer: a set of rotating cups that spin faster in stronger wind. It measures wind speed (velocity).
• Slope gauge: measures the steepness or inclination of the land.

Step 3: Match the instrument to the quantity Wind direction → wind vane.

Step 4: Answer The correct option is B. wind vane.

Exam tip: Remember the pairs:

• Vane → Direction (both are about pointing)
• Anemometer → speed (the cups spin round)
• Secchi disc → water clarity

JAMB often puts the anemometer next to the wind vane to catch students who mix them up.