Moodle has an "assignment" activity that lets students submit assignments electronically and lets instructors grade and provide provide feedback to the student. Students cannot see each other's assignments, so a wiki, blog, or forum are better choices if you want students to submit work that is to be shared with the class.
Go to your course and turn editing on. Add an "Assignment" activity.
General: Give the assignment a name and fill in information about the activity in the description.
Assignment settings: set up the due date and optional opening date cut-off dates. If you enable the cut-off date, students will not be able to submit their work after that time. There are lots of other options here. You can click on the question marks next to the choices to get more information on what each control does.
Submission settings: Select what type of assignment you want. The main choice is whether you want students to enter online text in a box in Moodle or upload a file or files (or both).
Feedback Settings: Enable feedback comments or files here. An instructor can send a feedback message to a student or upload a response to the student. For example, it is possible to download a student's MS Word document, turn on track changes, enter feedback right into the file, then upload the marked-up file as feedback to the student.
Grade: If using the online gradebook, can set up grade information here. If you are not using the Moodle gradebook, but will be providing feedback, select something other than "No grade" so that the grading and feedback screen appears.
Common Module Settings and Restrict Access: usually no changes required
Students will see the assignment link from the front page of Moodle. They will be able to click on the assignment and enter their text or upload their files. Moodle will give the student information about the due date and the current status of their submission (not yet submitted, submitted, graded, etc).
Grading and Providing Feedback for Student Work
After students have begun to submit their assignments, instructors can click on the assignment from the Moodle course page, and click on "View/grade all submissions." It is then possible to download all the assignments by selecting "Download all submissions" from the "Grading action" pulldown menu at the top of the page. You can also download individual files from within the assignment grade submissions screen (you may need to scroll the table all the way to the right to see the column with the links to the files).
To provide feedback or grade individual students, click on the "Grade" icon or link in the corresponding column for each student's record. Here you can see information about the submission, enter a grade, feedback comments, or upload a feedback file.
Changing the total number of points for an assignment
If you need to alter the point value of an existing assignment, make the change by editing the settings of the assignment itself. It isn't possible to change the point totals from within the gradebook.
It is possible to grant an extension to a student by going to View/Grade all assignments and clicking on the icon in the Edit column of the student. You can then select a new due date. The new due date is shown on the status column when viewing all assignments.