I recently went to a scout training and heard this great idea for learning the scout law. This would be great as a gathering activity. As the boys arrive they can join in the circle. One boy starts with the tennis ball and says "A scout is trustworthy", then he bounces the ball in the circle to another boy who says "A scout is trustworthy, loyal" and then he bounces the ball to another boy and continues with the next word. This is a great way to prepare the webelos to learn the scout law since it is a requirement to earn the Arrow of Light.
Once all the boys arrive, then you can proceed with den meeting as usual. We like to have our Denner assign a boy to offer a prayer, assign another boy to lead us in the pledge/flag ceremony, and assign another to lead us in reciting the scout law, oath, sign, handshake etc (ideally we do one or two at the beginning of den meeting and one or two at the end).
In our den we say the prayer first, this way it shows the boys that God comes first in our lives before country (the pledge) and den (the scout law etc).