Numberblocks 1-4 have a picnic. Four brings four flapjacks, but Three miscounts them as 3. They think one's gone missing.
Three explains to them that there's a flapjack snaffler - it's a strange creature made of three blocks, and has three eyes to spy flapjacks, three arms to grab flapjacks, and three mouths to eat flapjacks - in the picnic area. Four counts the four flapjacks, so they think they're safe.
Three counts 1-2-4-3, and thinks one's gone missing again. They hide behind a wall and see something coming. It has two eyes, two arms, one mouth, and five blocks. Three miscounts them as 3. They think it's the flapjack snaffler, but it's only Five! She asks Three is she knows how to count.
Look at a bunch of things.
Say some numbers.
Say 3 because 3 is the best number.
Five tells her the proper rules of counting:
Count everything once.
Say the numbers in the right order.
The last number is how many.
Three counts the four flapjacks properly. After the Numberblocks cheer for her, Four says he packed an extra one for Five, but it's gone missing. The rest of the flapjacks are gone, too. Everyone wonders who stole them without noticing the Flapjack Snaffler behind them, happily eating their flapjacks.
This episode has the most distorted faces. It is possible that the animation is a lot more sloppy than in other episodes.