BLOCK-CHAIN BASED GRADING STUDENTS ASSIGNMENTS

In this paper, we describe an innovative method of grading practical assignments for a big university course. This is quite usual nowadays that some university courses are taught for hundreds of students simultaneously. To accomplish the practical part of such courses, students are requested to implement practical assignments or projects that must be done in collaboration with other students, i.e. by working groups.

Grading of such student’s projects is done by a special team consisting of teachers and student assistants.
We have implemented a special software component for the learning management system that can be used to automate the previously described grading task. The architecture and usage scenario of the component was inspired by sound principles of so-called block-chain applications.

Thus, the grading process is organized as follows:
• Teachers define a standard structure of the students’ assignments. For example, in the case of database projects, the assignment must consist of a database schema in 4th Normal Form, a number of queries in terms of Relational Algebra, a number of queries in terms of SQL with sub-queries, a number of queries in terms of SQL without sub-queries and a number of PHP scripts.
• Teachers define requirements for each task. For example, there must be three SQL queries, one of them must illustrate “Group By” clause.
• Teacher define topics for student’ projects.
• Students enrol for particular projects, distribute tasks between the group members and implement the selected tasks. If the task is allocated for more than one student, the students provide the percentage that reflects an amount of work done by each of them.
• Finally, the teachers allocate particular tasks to the student assistants and provide each student assistant with a number of points he/she can distribute for the designated task.
• Each student has a special electronic “wallet” where he/she keeps points got for different tasks.
• The points are distributed by means of two types of transactions.

The student assistants allocate a certain number of points for particular task implementations. The points are further distributed between wallets of all the students that implemented the task.

All the process is implemented as a number of point’s transactions between electronic wallets. The transactions are gathered and secured into so-called data blocks, data blocks are arranged into a special block-chain structure. Transactions are verified and new blocks are created (mined) exclusively by teachers.

Thus, the scenario guarantees the fairness and homogeneity of the grading process because the assistants just grade particular tasks, and the whole project is graded by a substantial number of assistants. The results are verified on the obligatory basis since the validation and generating new protected blocks is a primary task of teachers in this scenario. The results are well protected from any kind of malicious attacks since the results are kept as a block-chain structure and any unauthorized modifications will be immediately detected as a property of the block-chain data structure.

From the student’s perspective, the electronic wallet provides all the necessary information on the flow of the assessment process.