Type the correct answer in the box. Spell all words correctly. Two students measure the dimensions of a single-storey structure. One takes measurements from the outside, while the other takes measurements from the inside. The students discover that their measurements for the height of the wall vary. The dimensions of the height of the walls are greater when measured from the outside than when the same walls are measured from the inside of the structure.

What is the explanation for this difference in wall height?

The walls have a greater dimension in height when measured from the outside of the structure because of the presence of a __
.