Hello Mr. Wood! :) Its Emma from your 6th period class! :)
My answer to the questions are:
The graph is showing around 386-388 CO2 concetration
On May 12th, it looks like the CO2 was measured when the sun was coming up (or dawning), so I'd say the answer is the time of day u measured the CO2 was either at dusk or dawn
I think the graph will go down because the sun is dawning which has the CO2 stuff go down because thats what it said on your graph thing :)
I hope you're having a fun time in Alaska and I hope you enjoy ur "grizzley burger!!! :) See you in a couple weeks! We miss you! :) -Emma