A Break in the Axis

So basically, I'm almost complete with my SRP. I just have to do some touching up. I was planning to bombard Mr. Ryan with questions today about my SRP, seeing that I had science for 3rd period, but he wasn't here and apparently isn't going to be here for the entire week. One of my most important questions was about my graph. I was wondering whether the y-axis HAD to start at zero (0). Since my experiment results were the highest temperature of the boiling water, the results are in the low 100°C and when I graph it starting at 0, the results are so much more crowded and harder to read compared to when it starts at, say, 96°C. I am pretty sure it has to start at 0 and usually when this occurs, I just draw a break in the axis (that squiggly/jagged line) but due to my lack of knowledge in Numbers & Excel, I don't know how to do that. I searched it up on the internet but the explanations looked so complex and complicated. Hopefully I'll find a way around it. I'm trying very hard to finish this assignment tonight so I can send it for checking but in the slight (likely) chance that I don't, I might just have to finish it to the best of my ability and not get it checked.