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?

Both the size and color of vinegar cubes changed.

Explanation:

The agar cubes before the addition of vinegar looked pink in color due to the addition of coloring agent for testing color change on addition of vinegar.

When vinegar is added the color  of agar changes from pink to orange as vinegar is acidic in nature.

Also as the vinegar diffused into the cubes it became large after stirring. Thus, both the size and color of vinegar cubes changed.