Does water expand in all directions to take the shape of the container it is in?

True, in a way. Water doesn’t really expand. It spreads out to take the shape of whatever container it’s in. However, there has to be enough water for this to happen. If you have a small cup, it doesn’t take a lot of water to get a good layer on the bottom half of the cup’s interior surface. If you have a large bucket, it takes longer to fill it enough to see a thin layer on the bottom of the bucket.

This isn’t a trait that is exclusive to water, though. Most liquids will spread out and run unless they have a container to hold them. Ever wonder why when you spill milk, orange juice, or even soda, it runs in the direction you spilled it and then some? This is why.