Imagine you and your friends want to vote on what game to play at recess. You have 10 friends, but there are only 3 games to choose from: soccer, tag, and hopscotch. You all get a piece of paper and a pencil, and you write down your favorite game.
Now, let's say you all agreed to use preferential block voting. This means that instead of just picking one game, you rank the games in order of preference. So, on your piece of paper, you write "1" next to soccer (because that's your favorite), "2" next to hopscotch, and "3" next to tag (because that's your least favorite).
Your friends all do the same thing. Then, you all put your papers in a box and your teacher counts up the votes.
Here's where preferential block voting comes in: instead of just adding up how many people voted for each game, your teacher first looks at everyone's first choice. If one game has the most first-choice votes, that game wins.
But let's say no game has the most first-choice votes. In that case, your teacher looks at everyone's second choice, and the game with the most second-choice votes wins. If there's still no clear winner, your teacher goes to the third choice votes, and so on, until one game comes out on top.
This way of voting is called "preferential block" because you're ranking your preferences in blocks (1st choice, 2nd choice, etc.). It helps make sure that the game you all play is the one that most people are happy with, because it takes into account everyone's individual preferences.