YOU SAID:
I'm going to middle school after summer break!
INTO JAPANESE
夏休みが終わったら中学校に通います!
BACK INTO ENGLISH
After summer vacation, I will go to junior high school!
INTO JAPANESE
夏休みが終わったら中学校に進学します!
BACK INTO ENGLISH
After summer vacation, I will go to junior high school!
That didn't even make that much sense in English.