Now I'm just reading master grade level.

本人如今在读硕士一年级。

It is written on a high third-grade level.

这是写在一个高的三年级（high third-grade level）。

I hope you don't mind my fourth-grade level Chinese writing.

希望您们不要介意我中文程度只有小学四年级。

With the rising of grade level, the reading ability of pupils is also rising.

随着年级水平的提高，小学生的阅读能力水平也随之提高。

The goal is to help all children read at or above grade level by the end of 3nd grade.

这个目标是要帮助所有的小孩在阅读上达到或超过年级水平在三年级末的时候。