This is a fun inertia activity for your students to try.
A flask (or bottle) set on the table.
The inner ring from an embroidery hoop* balanced on the opening of the flask.
Sugar cubes, in a stack, on the hoop, so they are directly over the opening of the flask.
Knock the ring out of the way, so the sugar cubes fall directly into the flask.
Some of your students will really get the hang of this and be able to get a sizable stack of sugar cubes to fall into the flask.
You can also stand a dry erase marker on top of the hoop and try to get it to fall in.
*Embroidery hoops can be found in craft stores (AC Moore, Michael's, JoAnn Fabrics, etc.). They consist of an inner ring, which is a perfect circle, and an outer ring, which has a screw closure to tighten it. Most of them are made of wood. You can sometimes find plastic ones or if you're at a thrift store/yard sale you might find some metal ones. For this activity, you can only use the inner ring. I haven't found anything that requires only the outer ring yet - still looking!