A few years ago, I taught probability to sixth graders and there was a game like this one in the curriculum. The objective of the lesson was the theoretical probability of a sequence of events. This is well above what my fourth graders need to know.
I liked the game and adapted it to be more appropriate for this level. To download a copy of Guess the Order from my Google Drive, click here.
Students cut out the four cards at the bottom, shuffle, and place in a single pile face down. They record the order that they think the cards will be turned over. Then they write down the number they guessed correctly. The trick is in figuring out what is a likely outcome for this game and what outcome is impossible.
I hope your students enjoy experimenting with probability in this way.
Update November 2015
In this packet are seven “carnival games” students will evaluate based on likely and unlikely outcomes. I have included a tri-fold page with the words “likely, unlikely, and impossible” so all students can respond at the same time in class discussion.