One way to structure your writing to inform is by using a diagram like this:
This is a timeline - the arrow is time moving forwards and the three lines break down the different events in order.
If you think of four events as being key things that happened in a certain order, then you could plan your article in that same order. For example, on the timeline the following could be the four key events that you could write about:
You could start with what actually happened so that the reader knows what the article is all about. From that point, you can then go back to the past to explain how this all came about. You can then return to the present and then move to the future.
It would be also be fine to go from the past, to the present and then to the future – as long as you start the article by explaining what has actually happened.
Once you have a timeline plan, you can then start to think about how all of the various conventions and ingredients will fit in. Some, such as a lively formal style will apply to each section and others, such as the use of a headline and subheadings need to be added when and where required.
This is now a plan that you could use to help you write your own informative article for the school magazine. As you go through the four key areas, you should keep in mind the key conventions that you have in your list.