Conclusion
I have found out that the most important material to make the lava lamp is the fizz tablets. Also that if you change the size of the bottle from one liter to two liter, but nothing else, then the one liter gets more bubbles. The reason that happens is because, since you don't change any other variable, like the oil, there is a lot of empty space in the two liter bottle. As a result, there is not much pressure so the bubbles just evaporate. In the one liter bottle there is no empty space so there is lots of pressure, that pushes the bubbles right back down so they keep going. If I would have accidently put not enough water, the measurements would have been way off, as a result that would have messed up my experiment. Next time I should use a clearer bottle for the two liter bottle. My results came out to be one liter bottle= 1 1/2 inches, and two liter= 1 inch, on the first trial. On the second I got the same results. On the third for the one liter I got 1 1/3 inches and the two liter 1 inch. Next time I would like to research about what would happen if I left the cap open. The highest data I got was 1 1/2 inches, and the lowest was 1 inch. That is what I learned in this year's Science Expo.