You hold some soil in your hand and notice how sandy it feels. what soil property are you observing?

The soil property that is been observed is SOIL TEXTURE.

Explanation:

There are different types of soil and each one has its unique characteristics. The characteristics of soil include: texture, structure, porosity, chemistry and colour.

Soil texture refers to the property of the soil, which indicates the relative constituent of various particles of diverse sizes that are present in the soil. The soil textures determines the amount of air and water a soil can hold and influence the rate at which water pass through its particles. It also determines the ease with which the soil can be worked upon. Soil texture can be determined by rubbing the soil particles on one's fingers.

thermophiles, notice the prefix thermo.