Here is my guide:
Sometimes bad grades are do to not very well study habits or even nervousness.
In AP style, you should write "eighth grade" when referring to the grade level. The term is not capitalized and should be spelled out in full. For example, you would say, "She is in the eighth grade." If used as an adjective, it would be "eighth-grade," as in "eighth-grade students."
indefatigable
I'm guessing 0.8-0.10
Although the average is supposedly at an eighth grade reading level, the actual level is somewhere between a 5th and 6th grade reading level.
9th and 10th grade
5 secentes
Ready Level E is typically designed for students in 4th grade. It focuses on developing reading comprehension and vocabulary skills at that grade level.
Yes, you hyphenate grade level when it is used as a compound modifier before a noun. For example, you would write "fifth-grade students." However, when it stands alone, such as "The students are in fifth grade," no hyphen is needed.
Prentice Hall Literature Gold Level is typically used for students in grades 9-12, or high school level. It covers a wide range of literature genres and works designed to challenge and engage students at that grade level.
Students typically learn about fractions in school around the 3rd or 4th grade.
lowest in history
I assume you mean funbrain... The eighth grade code is "lazy8"