As Chris King vigorously shakes the plastic container clutched between his hands, he appears to be mixing a cocktail for the assembled guests at Our Dynamic Earth in Edinburgh. But when the director of the Earth Science Education Unit removes the lid and tips up the tub, out come three stones he has been knocking against each other.
"This one is undamaged," says Mr King, holding it up for all to see. "This one is a little the worse for wear. But this one," he indicates the sorry remains of the third rock, "has just fallen apart.
"So we see that different types of rock wear at different rates. Hills like that one outside," he indicates the near-vertical crags of Arthur's Seat through the window, "are made of the same hard stuff as this - igneous rock. That's why they are still up there.
"Down there," he gestures through the opposite windows at the flat grounds of Holyrood Palace, "are the much softer sedimentary rocks, like the one that fell apart. That's why they are down there.
"Where rocks are hard you get hills. Where rocks are soft you get valleys.
Where rocks are hard you get headlands. Where rocks are soft you get bays.
"We have just explained all the ups and downs of the British Isles and all its ins and outs, and in the classroom we'd have given kids something to take away with them for the rest of their lives."
For a long time geology has been the poor relation of school sciences, languishing largely outside the curriculum - except for small sections of 5-14 environmental studies - while physics, chemistry and biology occupy privileged positions within it.
This is unfortunate since it was Scots such as James Hutton (1726-1797) and Charles Lyell (1797-1875) who more or less invented the subject. It is also ill-advised when school science is seen as irrelevant and difficult by growing numbers of children, who relate far more readily to the hills and valleys around them than to the periodic table, Newton's laws or the alimentary canal of the frog.
So the free resources and training workshops launched in Scotland last week by the Earth Science Education Unit, based at Keele University, are a timely addition to the armoury of teachers trying to convince children that the natural world is at least as fascinating as the digital one.
The unit, launched two years ago with funding for five years, has so far delivered almost 400 workshops in England and Wales. This experience was invaluable in developing resources for Scottish schools, says Mr King. "The 5-14 science curriculum already contains some geology, so while the original ESEU project was specifically for secondary science teachers, in Scotland it is aimed at upper primary."
The unit has developed two two-hour interactive workshops addressing the guidelines for Materials from Earth, level D. "Science Through the Window" uses hands-on classroom activities and everyday illustrations - "We can see some of the school building from the window and parts of it are probably crumbling away" - to investigate the atmosphere, soil, weathering, erosion and landscapes. In each section, learning outcomes are related to 5-14 attainment targets.
"Scotland's Journey" tells the story of the land beneath us and interesting events that happened during the passage of 600 million years (such as colliding with England) that can be read in the rocks.
The story of the professional development programme and resources is almost as eventful, though shorter.
"As a geologist, I kept getting asked if I could put together rock kits for schools," says former teacher and Northern College lecturer Peter Craig.
"So we assembled a kit of rocks and comprehensive notes which went out to Grampian and Shetland schools.
"We then talked to Scottish Natural Heritage about "Scotland's Journey" and to Learning and Teaching Scotland, who recommended we produce a resource for all teachers of 5-14 science. It all came together when the ESEU became part of the partnership, bringing their experience in England and Wales with them."
The two workshops, developed in collaboration with the Scottish Earth Science Education Forum, will be organised through the education authorities and delivered by 11 specialists around the country. Teachers will be able to try out the activities and then take the resources - a map, rock kit and CD-Rom -back to school with them, free.
"We know that just providing resources doesn't do it for schools," says Mr King. "You have to produce things that are tailor-made, show teachers how they work and give them stuff they can take away and use in the classroom tomorrow."