Hi Mr. Wood~! This is Cameron from your 2nd period class. Here are my answers to the May 14th Journal.
It seems the graph is showing about 387 CO2, but some go down to 386 and 388.
Maybe during the afternoon, somewhere around 2 p.m. and 3 p.m.
In two hours, there would be less CO2, because the plants would've already used the CO2 in the morning.
Hope they are right!(-: