Reward Systems in Classrooms

One thing I have discovered in my field placement this year is that my CT is BIG on reward systems in her classroom. At the beginning of the year she would do a different type of reward system every week, which has turned into a monthly reward system. The students are divided into 7 or so different groups that are based off their reading levels. One week she had small plastic cups that she would fill with marbles or pebbles if she saw a group doing a good job. She has also used a sticker system where the students needed 20 stickers by the end of the month to be apart of a class party. Right now she is implementing a bead reward system where each student has a container that they will is being filled up with green and red beads, which will be used to make a necklace at the end of the month. So if the students are doing their work and behaving in the classroom then they will receive more beads to make their necklace with. I question the way my CT rewards the her students because she will tell the students that they will earn 5 beads if she sees the group working well for the next 20 minutes instead of rewarding the students for doing a good job after the fact. There is sometimes 3 different systems going on at once inside the classroom, which I think could be confusing for the students. There is a sticker chart on the doors of her classroom for each student, there is sometimes a group reward system, such as the cup and pebble one explained earlier, and another system where students get a star or sticker to put on their sheet, which they keep on their desks. Also there is constant competition between the boys and the girls, where if the girls are doing well then they will get a sticker and also a competition between the different groups of students, as well as a competition between individual students to see who can collect the most stickers or beads. There is too much rewarding and competition that is going on in this classroom that I think is taking away from the learning, which should be the most important thing in a classroom.
I'm not sure how I feel about reward systems in classrooms because I think this is taking away from the fact that students are being extrinsically motivated to learn instead of intrinsically. The students are not learning because they want to, but because if they don't participate or don't get the question right then they won't get a bead or sticker. This also includes behavior where students are behaving well in the classroom because then they will get a reward instead of behaving correctly because it is the right thing to do. I think that if you have one type of reward system where students are being rewarded with sitting in a special chair to read a book instead of giving students stickers, food or toys that this would be more affective in the classroom. Rewards should be helping the students further develop their skills or learn even more and not fill up their stomachs or giving them an object to play with. There seems to be a fine line with rewards systems in classrooms and it is important for teachers to use them the correct way and to not cross that line so students are not motivated just based off of what fun thing they will get in return.