Knock the Balls Down Nerf Target Game - Super boredom buster, and a fun party idea too.
Build a Marble Run with Craft Sticks - Great STEM challenge for kids! Marbles, craft sticks, and cardboard boxes.
Paper towel rolls, Tape, Marbles and/or bouncy balls
Prune & Violette: Trois bouts de carton (et un peu d'imagination)
Met kosteloos materiaal
Make board activities for smaller kids, store in something like hanging folder or vertical shelf or pin to a wall or ...
Using pieces of pipe cleaner as worms and clothes pegs as bird beaks is a very easy way to work on developing those little hand muscles and fine motor control!