I've been intrigued with the concept of subitizing or "instantly seeing the quantity" ever since reading about it in a recent issues of Teaching Children Mathematics. I've started using our DIY counting rope to flash quantities in front of my 5yo. Want to join us? If you're a homeschooler, just make a counting rope and pull a small number of beads to one end. Then hold up the rope for a brief look (long enough to see the beads but not long enough to count each bead individually.) Teachers could put the counting rope under a document camera or lay game chips on an overhead for a similar experience.
Then, extend learning with this "Speedy Pictures" game. You can choose to flash a visual representation of a number using fingers, dice, rekenrek, eggs, or number discs. The flash time may be increased or decreased, according to student needs. Students get a moment or two to see the quantity--but not count one by one--before being asked to enter a total. This activity would make a great computer-based Math Station.