Computing for Kids

I need to demonstrate/explain Computing to young children (9 years of age) in a fun/interactive way. I thought of the following group exercises:

Find Median - split children into teams of 7 or 9, have each team make a line, give each child in the team a number (in no particular order), ask the children in their teams to work out the middle (median) number. The key is for them to first assign a captain and order themselves by their numbers (highest to lowest or lowest to highest).

Bubble Sort - split children into teams, have each team make a line with each child spaced out from the next by one metre, give each child in the team a number (in no particular order), ask the children to sort themselves (highest to lowest or lowest to highest) by only being allowed to speak to the person immediately in front or behind. Can't get around this problem by assigning a captain!

Resource Allocation - split children into teams of 7ish, have each team make a circle, give each child in the team an item (chocolate?) and a goal (item to obtain), ask the children to maximise the number of "happy" children in their teams. Need to think of cases involving conflict.