Ok so basically you square root the "Lengths " numbers at the top of the page. Using these answers ( the period/seconds numbers) you plot a graph
So, square root of 1.00 is 1
Square root of 1.96 is 1.4
Square root of 3.24 is 1.8
Square root of 4.00 is 2
Square root is 4.84 is 2.2
Square root of 6.25 is 2.5
Square root of 7.29 is 2.7
Square root of 7.84 is 2.8
Square root of 9.00 is 3
Then, you plot the numbers on the y axis. Also, did your teacher give you a specific graph to draw (such as a bar graph, column graph,line graph, etc?) because I'm not sure what graph you should draw. Hope this helps ;)