question about 2GI3 lab, which lab is the hardest or takes the longest time to finish?

Lab 6 is the longest/hardest lab, it is a lot of analysis and map making. Lab 4 is the second longest because you have to digitize buildings on campus. If you run windows, you can install the software on your computer and the length of the summer course would fall well within the free trial period (otherwise the license is cheap for a year). I really liked using my own computer vs. going into the GIS lab.

was the midterm harder than the exam?

After asking about 2GI3 quite a lot - it's cool that you're finally taking it. I took the course with Dr. Scott and I found the later labs harder and the exam easier.

These might have some general pointers to quell your concerns...
Old course review with Dr. Scott (which I doubt has changed too much): http://www.macinsiders.com/showthrea...tr=E&t=25 341
Course review (more like a discussion) with Pat Deluca:http://www.macinsiders.com/showthrea...tr=G&t=46 641