I agree with the other posters.. to play with thermite...is out of the question ..especially since you said you are 14 meaning this is most likely your first chemistry course..and if you want to play with sodium you probably need a few more years lab experience...ive had a home made peice of potassium metal smaller then the tip of my pinky explode when placed in a small container of water..granted it wasnt a large explosion but a shard could have easily gotten in my eye.
actually interestingly enough that happened in my highschool when i was showing off a peice of k metal that i had made to my biology teacher...unfortunately she was talking to some lady at the time ...the lady turned out to be the dean of science... to say the least the dean of science was freaked out that someone had brought potassium to school and it did not look good for the teacher... luckly no one got in trouble.. but that is a prime example of what not to DO ...dont be stupid like me!
making thermite and alkali metals at home is very dangerous...