To introduce the Beavers to the idea of collecting
Printed Lego Guess Who cards - available here (at the time of writing)
To introduce the Beavers to the idea of collecting, for their Collecting Badge, print off the Lego pictures, and use them in a relay-style game
e.g. collect all the Harry Potter characters
collect all the characters with glasses
collect all the male characters
this will introduce the idea that collections should be of similar objects, or with a specific theme.