Hi, a constructive/building activity in soil/sand/water with digging, pouring, compacting, turning out, joining, uncovering, collecting hide & find resoures are all good for sustaining the shared thinking associated with discovery and investigation.
What goes where, how, what happens, will it fit, big, small, tight, loose ..
This publication on praticalpreschool
'Using projects to sustain shared thinking has good reading as does the
project approach to early years provision on amazon
Hth, best wishes xx