Ice jam

Okay kiddo, an ice jam is when a bunch of ice blocks get stuck together and form a big icy dam in a river. Just like when you play with your toy blocks and stack them on top of each other, the water in the river can make the ice blocks stick together too.

Here's what happens: when it's cold outside, the water in the river starts to freeze and turn into ice. Sometimes, the ice melts a little during the day when it's warmer, but when it gets cold again at night it freezes right back up.

Now, if there's a lot of ice in the river, it can start to pile up on top of itself, just like how snow piles up on the ground. Eventually, the big pile of ice blocks can get so thick that the river can't flow freely anymore, and it starts to back up, just like when you splash your bath water and it starts to overflow.

When the river can't flow, things can get dangerous. The water can start to rise and flood nearby areas, just like how your bath water can make a mess if it overflows. That's why people try to prevent ice jams from forming by breaking up the ice or using machines to move the ice out of the way.

So, that's an ice jam - a bunch of ice blocks that get stuck together and form a big icy dam, which can cause a lot of problems if it blocks the river and makes the water rise up and flood nearby areas.