The technology “blockchain”, in English “chain of blocks”, has been known for several years – especially since the success of Bitcoin. The education industry is also gradually becoming interested in this technology and exploring the first possible applications. A look at initial approaches and other possible use cases.

## Blockchain: A chain of information

Blockchain is a chain of information. Depending on the industry in which the blockchain is used, the information involved is very different: In the financial industry, account numbers or purchases made are stored in the blockchain, in the real estate industry it consists of rental contracts, rental payment confirmations or ancillary cost statements. In the education sector, for example, it is assessments such as grades or the individual solution to a math problem. But what are the advantages of a blockchain? To answer this question, three properties of the blockchain are important: its sequence, its network, and its security.

## Blockchain: the order is crucial

In the blockchain, all information is chronologically linked in a chain. Each piece of information is stored as a block – as a link in the chain. An example: Two pieces of information about a student, the mathematics exam on March 21 and the censorship: 11 points, are linked together. The blockchain provides both pieces of information with an encrypted check digit, a so-called hash, and a time stamp. This hash is now the same on block 1 – mathematics exam on March 21 – and block 2 – censorship: 11 points – the same.

That means: Block 1 and Block 2 are inextricably linked, only Block 2 can follow Block 1. The order of the blocks is therefore exactly determined. If many blocks are chained in this way, a blockchain is created. Taking the math grades as an example, it could look like this: „Certificate grade 1st semester: 12 points – Math exam on March 21 – Censorship: 11 points – Exam on May 14 – Censorship: 9 points – Math exam on July 3 – Censorship : 13 points – Certificate grade 2nd semester: 11 points “.

Blockchain as a network

A blockchain like this is part of a network. You need a special program to enter the network with your own computer. Members of the network for the math blockchain from the example above are all persons who are related to this student’s math exams, for example the math teacher, the student, the math examiner, the headmaster and others. A scenario: The student from the example above is dissatisfied with his grade, 11 points in mathematics, because he is aiming for a degree with a high numerus clausus. Shortly before the grades close, he sneaks into the staff room and forges his own math grade in the grade index of his course: He gives himself 13 points. Such manipulation is not possible in the blockchain. Is someone trying to change the blockchain this is immediately registered by the blockchain network. If only one block changes, e.g. censorship, within the blockchain, the hashes – the check digits – of the adjacent blocks no longer match.