How do fluids move within rocks or sediments? And how does this movement relate to engineering applications such as geothermal energy extraction or oil and gas production? During this hands-on experiments activity students will get familiarised with the concepts of porosity (pore space within porous material) and permeability (ability of porous material to allow fluid to pass through it) as well as with the concepts of capillary action (ability of a fluid to flow along the pores against an opposing force such as gravity). This will be a one or one and a half hour session (depending on the number of students).