Record your observations of how the agar cubes look before you add vinegar and then after you add vinegar and stir. How did the appearance of the cubes change over time?

The vinegar would tend to diffuse into the agar blocks decreasing the amount of vinegar outside the agar cubes and increasing the volume of agar cubes. Diffusion is the movement of particles (ions or molecules) from an area of higher concentration to an area of lower concentration.