I think your mom suspects you really COULD ace the Language Arts Test, and to get silkies, which you want very much, you would work VERY hard toward studying and preparing for the test. She also knows you want to keep your other chickens AND get silkies -- so she's using MOM psychology on you.
Psssttt.... Langauge arts -- WRITE an explanation for your teacher of what your mom's reward plan is, and ask her for help preparing for the quiz. Most teachers really WANT to help students learn, but they save their best efforts for the students that show them/let them know that they really want to. And, you can post your "written explanation/request" for the teacher here, and we'll all help you edit it and check the spelling, etc., etc....before you turn it in. And, if your teacher is REALLY cool, she'll count your written piece in place of your next quiz grade!!!!
ETA: Oh, yeah, that's a SILKIE hen on my head in the avatar -- her name is Charlemagne, and her mate is Elmo!