If you really want to keep the kids busy, why not get them to make their own beanbags first by sewing two small rectangles of scrap fabric together before stuffing with dried beans or lentils! Beanbag toss involves a "course" which the children can set up themselves or you can provide for them, so you can make it as easy or as challenging as you like!
Start by setting up a course - either with or without the help of the kids. Use cushions or pillows as markers, and find some containers - waste paper baskets, buckets, empty shoe boxes etc - to be targets or "golf holes".
Now the children take turns in tossing their beanbag around the course and into the targets as appropriate.
One child can play against himself by trying to improve his score, toss from further away, and so on.
You could use a series of containers, set further and further away, as a series of targets, giving each one a point score depending on how far away and hard to achieve it is.
NB: make sure that you state the rules clearly or supervise to make sure that your room stays safe! Breakables and pets should probably be moved out of the way for safety!