It's too short and too vague. Here's what my cover letter sounds like (edited heavily for privacy, adapted in light of what I know about US education, and not proofread at all!):
Please accept the following resume in response to job posting #9999, for the position of Elementary Teacher. I believe that my broad range of elementary student teaching experience and relevant university education would be of great value to Your School.
I have recently completed three different elementary school student teaching practica, including two months spent teaching Language Arts and Social Studies to third-grade students at Neighbouring School (NS). At NS I delivered programming based on the Common Core curriculum, which was differentiated to meet the needs of students learning English and students on Individualized Program Plans. I worked closely with the school's reading specialist, and volunteered at a weekly after-school Reading Club. I also completed a one-month practicum placement at Other School, where I taught an inquiry-based science unit about weather to students in grade six. I engaged students in this exploration of weather by inviting a meteorologist to the classroom, and by using green-screen technology to have students film their own weather forecasts. Prior to entering the Education program at Your University, I volunteered as an after-school tutor with the Boys and Girls Club of Your City, and worked as a camp counselor with the YMCA in 2014 and 2015. Through my volunteer work I learned the impact that a positive relationship with an adult can have on a young person's ability and willingness to learn.
In April 2016 I graduated from the Bachelor of Education program at Your University. This program helped me develop skills in lesson planning, instruction, assessment and classroom management. I sought opportunities to extend my classroom learning by attending professional development events put on by the Education Student Society, including Important Workshop A and Interesting Workshop B. My on-campus learning, combined with my student teaching experiences, prepared me to enter the teaching profession with confidence and competence.
I look forward to speaking with you about this opportunity. Thank you for considering my application.