It depends on how you want to format your data table, as you can create as many columns or rows as you wish, but the important thing is, to display your quantitative data suitably and in the most simple manner. The main reason why data tables are even used, is to simplify and represent the data in an easy to interpret and access form. If your data table has two columns, then the left side would likely be the manipulated variable, or also known as the independent, and the right side would be the responding or dependent variable. To determine which is which, just look at your data and see which one is manipulated (changed) in order to make the other one "respond" or react to the changes (responding variable). In your case it seems that you do have two units, therefore two "sets" of data, so make sure you know which is which. Also, when you put it into your data table, ensure that you put your units in the top labeling row, so you won't have to rewrite (m 3) for every row of data. After that, it should be fairly easy to input your data and such into the table.