1) You are given a test at school that has questions that teacher hasn't covered yet. In the middle of the test you notice that your friend next to you has a cheat-sheet. The teacher doesn't notice.
If it's the teacher's fault, then the chances are pretty good that the rest of the class won't get those questions right, either. So I'd do my best guessing, and then wait until the results come back so the teacher can see that something went wrong and try to get things sorted out from there...

2) While walking down the street you see a wallet on the side of the road. It has a small amount of money in it, but no identification of any kind. There is nobody in sight.
If there's a store or business nearby, I'd drop it off there for the owner to find. If not, I'd probably put up a poster where I found it with my number and see if anyone was trying to find it. I know how it feels to lose things, so I wouldn't want to just pick up someone else's stuff and walk off with it.

3) Someone has played a prank on you which involves your public embarrassment and everyone begins laughing at you. However, you doubt they meant any harm by it.
I'd do my best to laugh along with them in the moment, probably, but I would definitely confront them about it later in private and ask them not to do it again.

4) You have arrived late to work because you had a flat tire. You've been on time every other day for the past month, yet your boss yells at you about it in front of all your coworkers.
I'd have a really, really hard time doing it, but I would try my hardest to hold my tongue and keep my emotions in check-- because I'd just end up doing more harm than good if I fired back at him. Plus, I've learned the hard way that you shouldn't give anyone the satisfaction of getting a rise out of you, because it only encourages them to keep going...

5) You're class has is splitting up to take part in different in volunteering activities around the community. You can volunteer anywhere you want.
A coastal cleanup! Or a wildlife rescue~

6) A little kid accuses you, in front of a whole crowd people, of stealing his toy which you did not do. You are twice his size, but he won't back off.
I'd tell him firmly to quit it, and if he didn't back off, just get away from him. I don't get along great with little kids in the first place-- plus hate liars, and being accused of things I didn't do-- but I can't very well get into a fight with a kid.

7) You have saved up for months to buy a new bike. As you're getting ready to buy it, a child runs by and steals your money. You chase him down and find that his mother is deathly ill and the child stole the money to buy her medicine.
If he couldn't prove it, I'd take it back. If he had proof, I'd give him some of it.

cool A friend of yours tells you that there is some really cool stuff in an old abandoned building. When you get there you see a sign that "Danger: Do not enter!", but the building doesn't look dangerous. There is nobody around to see you, and your friend wants to check it out.
Nah, they can do what they want-- I don't need any more trouble, that's for sure.

9) A very strong man approaches you while you're eating lunch and demands that you give him some food. He doesn't appear to be starving or poor. There is nobody there to stop him from taking it.
Like I said, I'd rather not attract any more trouble... I'd probably end up giving him some to get him to go away.

10) Your two best friends are fighting over a small issue. Each of them ask you to choose their side.
No, thanks-- I'm not getting in the middle of that. I might try to mediate a little, but ultimately I'd probably end up just sitting out entirely.