Any changes in length due to osmosis would alter the ratio of original length:final length to be either above 1 (more original length than final length) or below 1 (more final length than original length).

Concentration of the potato can be found via the graph when the ratio of original length: final length = 1:1. A ratio of 1:1 means no change in length of potato due to osmosis.

From your graph is around 5-10% sucrose concentration. If I’m not wrong the water potential is how much % water is in the potato which means if there is 5-10% sucrose, you assume the remaining 90-95% to be water— or “water potential”.

Also, you may want to reconsider the axis intervals it’s a bit weird and I think each small box should be even interval not odd interval.

Thank you so much I get it now!

The intervals are the best I can figure unless I had a taller graph paper

Understand but do check with your teacher again what is acceptable for the interval because I remember they do penalise if it’s not “even” or of “5/0.5” etc