The apparatus itself has changed very little over the years. There are five tubes embedded vertically in a long, narrow box. And there are two tubes embedded horizontally in the same box.
The boy on the left is using a syringe to pour sand down a tube. The girl on the right is also using a syringe, but she is also pouring sand into the syringe from a bottle. She looks like a scientist measuring the material for her experiment.
The children are always provided with a variety of scoops, containers and loose parts to use with their operations.
The beauty of the loose parts is that the children combine them in various ways to create their own tools for pouring. It can be as simple as inserting a clear plastic tube into the end of a bottle of sand to direct the sand into a tube.