Pupils use the net they make to dip macroinvertebrates at or below the surface. The flat side of the net allows pressure on the substrate so that organisms do not escape under the net. Two students hold onto the handles and submerge the net until the bottom edge is on the substrate. They should hold the net in place. A few other pupils enter the water upstream of the net and walk downstream, kicking the substrate to dislodge organisms which the current carries into the net.