学业负担一直是基础教育领域长期而沉重的话题。作业是课后学业负担的主 要来源之一。如何通过作业减轻学业负担是政策和研究关注的重点。长期以来的教育政策和研究大多以作业时间作为切入口，将缩短和控制作业时间作为减负的主要途径。然而，基于作业的理论基础，以情感态度、学习策略和课程内容为代表的质量因素对作业的参与程度和有效性起到重要影响。关注时间和质量对学生学业成绩的交互影响，有利于透过表象，通过“提质增效减量”，实现长期可持续的学业发展。

本研究从作业视角下的“量”和“质”两大方面出发，关注“量”和“质” 的因素对学生成绩的影响。以 2440 名八年级学生作为研究样本，以数学学科为例，采用广义倾向值的方法进行统计分析。

本研究共包含两个子研究:研究一基于总样本，使用广义倾向值分析构建数 学作业时间对数学成绩的剂量-反应函数，估计数学作业时间对数学成绩的效应。 研究二关注数学情感态度(包括数学自信、数学兴趣、数学焦虑)、数学学习策略(包括记忆策略、精加工策略、控制策略)和数学课程内容维度(即学生对数学内容熟悉度)下各个“质”的因素，基于各个“质”的因素的下四分位数和上四分位数将学生划分为低、中、高三组，在各组中分别使用广义倾向值估计数学作业时间对数学成绩的剂量-反应函数，以探究不同的“质”的因素如何与作业时间交互影响数学成绩。

本研究的结论如下:

(1)  在控制学校、家庭和学生层面的协变量后，数学作业时间与数学成绩呈倒 U 型的关系，随着作业时间的增加，学生的数学成绩先上升后下降。其中，45 分钟是达到最佳数学成绩的作业时间阈值。

(2)  增加数学自信和数学兴趣、降低数学焦虑不仅能直接提升数学成绩， 还能够通过缩短达到最佳成绩所需的数学作业时间，提高作业效率。

(3)  增加记忆、精加工和控制策略的使用频率虽然无法直接提升数学成绩， 能够通过缩短达到最佳成绩所需的数学作业时间，提高作业效率。

(4)  增加学生对数学内容的熟悉度不仅能够直接提升数学成绩，还能够通 过缩短达到最佳成绩所需的数学作业时间，提高作业效率。

Academic burden has long been a heavy topic in basic education. Homework is one of the main sources of after-class academic burden. How to alleviate the academic burden through homework is the focus of policy and research. For a long time, educational policies and research paid attention to homework time. Shortening and controlling homework time has been used as the main way to reduce the academic burden. However, according to the theoretical basis of homework research, educational quality factors including attitudes learning strategies and curriculum content also play an important role in the homework process. To promote the long-term sustainable academic development, it is conducive to focus on the interactive effect of homework time and educational quality factors on students' academic achievement.

From the perspective of “quantity” and “quality” of homework time, the current research recruited 2440 Chinese students in Grade 8. It took mathematics as an example and used the method of generalized propensity score (GPS) for statistical analysis.

The current research consisted of two studies. In the first study, the dose-response function of mathematics homework time and mathematics achievement was constructed using the full sample to estimate the effect of mathematics homework time on mathematics achievement. In the second study, three educational quality factors were in focus: attitudes towards mathematics (including mathematics confidence, mathematics interest, mathematics anxiety), learning strategies (including memorization, elaboration, control), and curriculum content (represented by the variable of mathematical content familiarity). Students were divided into different groups according to the first four quartile and the last quartile of each quality factor. In each group, the dose-response function of mathematics homework time on mathematics achievement was conducted to explore how mathematics homework time interacted with different quality factors on students’ mathematics achievement. The main results and conclusions of this research are as follows:

(1)  There was an inverted U-shaped relationship between mathematics homework time and mathematics achievement. With the increase of homework time, students’ mathematics achievement increased and then declined. The threshold of homework time that reached the best mathematics achievement was 45 minutes.

(2)  The increasing of mathematics confidence and interest, and the reduction of mathematics anxiety not only directly improved mathematics achievement but also increased the efficiency of mathematics homework by shortening the homework time required for the highest achievement.

(3)  The increasing use of learning strategies could not only directly improved mathematics achievement, but increased the efficiency of mathematics homework by shortening the homework time required for the highest achievement.

(4)  The increasing of mathematics content familiarity not only directly improved mathematics achievement, but also increased the efficiency of mathematics homework time by shortening the homework time required for the highest achievement.