Your 'measuring atmospheric pressure' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
your comment
How does the system behave and how does it 'feel'?
Squeezing the container will cause the water to rise somewhat and the pressure in the water will move to shorten the air. And if I squeezed really hard the water will rise in the tube and the air will come shorter.
Length of the air column in units of your measuring device:
50 cm. I chose this one because it will be an easy one to read and to deal with during the squeezing and pressure.
Your report of the vertical position of the first mark relative to the water surface of the first mark, the length of the air column in units of your selected measuring device, and the two meniscus positions observed with each of your five trials.
14 cm
looked in the vertical tube to see how much air was involved or in the tube. 30 to 44 cm. I just took the lengths and subtracted to get the length of the air in the tube.
Your report of the vertical position of the second mark relative to the water surface of the first mark, the length of the air column in units of your selected measuring device, and the two meniscus positions observed with each of your five trials.
10 cm
14 cm
20, 34 cm
12, 26 cm
15, 29 cm
29, 43 cm
18, 32 cm
Your report of the vertical position of the highest mark relative to the water surface of the first mark, the length of the air column in units of your selected measuring device, and the two meniscus positions observed with each of your five trials.
20 cm
33 cm
25, 36 cm
30, 41 cm
32, 43 cm
34, 45 cm
30, 42 cm
28, 40 cm
Your report of the vertical position of the 'in-between' mark relative to the water surface of the first mark, the length of the air column in units of your selected measuring device, and the two meniscus positions observed with each of your five trials.
Data look good so far.