The teacher does make a valid point in terms of work place environment though. Say you are working on a project for company ACME. Rough times have hit the company and now your team has went from 4 people to 2 people and the client is still expecting the project to be ready by the same date. You wouldn't be able to go to the client and ask for an extension because it can be taken as a lack of ability. If you tell the truth, the company recently let go 2 employees on the team, it shows the company may have some financial instability and the client may pull the project all together.
It sucks, I have experienced this in my previous job where I was on a development team of 10 and was chopped down to 4 while we were still expected to complete all the new projects while maintaining old projects all at the same time.
I have also experienced something similar with my senior college paper that we had to write as a group of 4 about 100 pages worth of information or about 25 pages each. 2 of our members decided the class was not worth their time and slacked off writing barely 10 pages each leaving much of the work to myself and another. We approached the teacher and luckily for us, the grade was based on our individual parts you did and not as a whole group.
This though, is not as practical as my experience I first described to you because in the real-world, a client isn't going to go to an individual worker and say hey! this project was terrible, but your part was great! They are going to go to your boss and say, this project is not what we agreed to, and not what we paid for. FIX IT. and you all get in trouble.
So while this may be a really lame situation, the teacher is actually preparing you for real-world situations that may come up. Of course if you still feel strongly that you should be given consideration/moved to a new team, there is always the option of talking to the dean or department head to find out what they can do. Usually though, they will stick to the teacher's choice.
With proper time management and understanding the priorities, you will find a way to get it done. Don't try to tackle it all on at once, but break it down into segments. if it is a 10 part project, talk it over with the remaining partner and sort them out. Which parts are you stronger at, which parts are they stronger at. See if you can balance out your weaknesses with their strengths and vice versa. From there see what is left over to do and see of the ones that you guys have mutual weaknesses on, which one of you feels MORE Confident in taking on one of the parts. From there just get working on it. You both know what you need to do, both know when they are due. If you cannot move forward with a part until they get their segment done, work on a non critical path item that you can do on the side that is not waiting for a pre-req to be finished.
Edit: To the person saying comparison to the business is silly and can always rehire... this is not entirely true. If a company let go people, the chances of them hiring anyone to take their place so you can get the project done is very unlikely. Rehiring in general is a long process that can take months to fill in the gaps. Are the workers just suppose to stop and wait for the new hire and blow all deadlines? No. That doesn't happen. Even if they start rehiring right away, you need at least a month or 2 just for interviews alone. New hires may not be able to start right away due to still being at old job or the have a prior commitment and cannot start for a time period. Working at jobs that isn't Mc'Donalds takes time to find suitable replacements with applicable experience. Again assuming that there is no hiring freeze which there probably is one due to being let go. not fired. there is a difference between let go and fired.