If the students have to write an adventure game they will probable have to include a stage where you have to cross a river or a road or the sea...
Here is some basic code to make it look like many different cars are passing by at different speeds, although you only need one sprite:
Make one new sprite - pick a car from the sprites under transportation. Then import other cars as costumes for this sprite. That means it will look like a different car every time you change to the next costume.
- picks a random speed
- change the costume so that it looks like a different car
- puts the sprite in the starting position (on the left), and
- makes the sprite move across the stage until it reaches the other side (right end of the stage).
Now you can try to make the chicken cross the road :-D