The Chalkboard is an object used as a drawing board for making plans or sketches.
Steven decides to build a spaceship with Greg. However, once the contraption was tested, it crashed. Pearl says that their "calculations were off," which leads Greg to point out that their calculations "couldn't be off if there were never any." In response, Pearl uses the chalkboard to draw a rough draft of a possible spaceship blueprint which comes to fruition.
At the barn, Pearl begins to draft a blueprint for the drill on the chalkboard but sees that Steven has already drawn a crude blueprint of the drill himself. Pearl then looks at the chalkboard and tells Steven that "it's a lovely drawing, but it won't look like this." Later on, Pearl and Peridot each build a robot to compete against the other to decide who should lead in building the drill. During this, Steven uses the chalkboard to count the points each of them made as they battle to see which robot is better.
Near the barn, Pearl calls out to Peridot to look at the layout for the drill, and Pearl uses the chalkboard to make the plans. Peridot asks her why she should be working for a Pearl, replaying one of her logs in which she states that Pearl has an intellect that she should be able to treat as an equal, though begrudgingly.
Pearl used it to put Pearl Points at the Ancient Sky Arena.