diff --git a/app/models/students_for_course.rb b/app/models/students_for_course.rb
index 35bb6613a..4027cd7db 100644
--- a/app/models/students_for_course.rb
+++ b/app/models/students_for_course.rb
@@ -40,7 +40,7 @@ class StudentsForCourse < ActiveRecord::Base
 
   #加入班级时创建一条记录
   def create_course_homework_statistic
-    if CourseHomeworkStatistic.where(:user_id => self.student_id, :course_id => self.course_id).count == 0
+    if CourseHomeworkStatistics.where(:user_id => self.student_id, :course_id => self.course_id).count == 0
       course = self.course
       user = self.student
       hw_count = course.homework_commons.includes(:homework_detail_manual).where("homework_detail_manuals.comment_status > 0").count
@@ -63,13 +63,13 @@ class StudentsForCourse < ActiveRecord::Base
       appeal_num = user.student_works_scores.where(:student_work_id => student_works.map(&:id), :appeal_status => 3).count
       average_score = user.student_works.where(:id => student_works.map(&:id)).select("AVG(student_works.work_score) as score").first ? user.student_works.where(:id => student_works.map(&:id)).select("AVG(student_works.work_score) as score").first.score : 0
       total_score = user.student_works.where(:id => student_works.map(&:id)).select("SUM(student_works.work_score) as score").first ? user.student_works.where(:id => student_works.map(&:id)).select("SUM(student_works.work_score) as score").first.score : 0
-      CourseHomeworkStatistic.create(:course_id => course.id, :user_id => user.id, :committed_work_num => committed_work_num, :un_commit_work_num => un_commit_work_num,
+      CourseHomeworkStatistics.create(:course_id => course.id, :user_id => user.id, :committed_work_num => committed_work_num, :un_commit_work_num => un_commit_work_num,
                                      :late_commit_work_num => late_commit_work_num, :absence_evaluation_work_num => absence_evaluation_work_num, :un_evaluation_work_num => un_evaluation_work_num,
                                      :appeal_num => appeal_num, :average_score => average_score, :total_score => total_score)
     end
   end
 
   def delete_course_homework_statistic
-    CourseHomeworkStatistic.where(:user_id => self.student_id, :course_id => self.course_id).destroy_all
+    CourseHomeworkStatistics.where(:user_id => self.student_id, :course_id => self.course_id).destroy_all
   end
 end