This study aims to fill a gap in middle school science education that no direct comparison has been conducted on three popular grading methods - point based, rubric based, and rubric plus written feedback based - on science achievement and motivation. Participants in this quasi-experimental study are 136 7th and 8th grade students from Midwest USA. Results indicate that for both grades, the written feedback group performs significantly better than the point-based and the rubric-only groups on both achievement and motivation measures. However, science achievement under rubric-based grading but without written feedback is not different from that under the traditional points-based grading, underscoring the important extra power that written feedback delivers. This study recommends that written feedback be highly relevant (to the academic standard being assessed), limited in number (to the major misconceptions students have), and giving a second chance (for students to act on to improve learning).