The mystery deals with sand that stays dry when water is poured onto it. Students are requested to find ways to build sand castles with this ‚dry‘ sand.
Chemical bonding, hydrophobic and hydrophilic properties.
15 to 17 years old.
Expected time for the mystery
Approximate time for teacher preparation: about an hour to prepare materials. About an hour to practise the story.Approximate time in classroom: between four to six periods of 45 min each: one period to engage and explore, one to explain, three for open enquiry, and one to present the enquiry in class.
No safety concerns. The materials are not toxic.Disclaimer: the authors of this teaching material will not be held responsible for any injury or damage to persons or properties that might occur in its use.
Preparation and list of materials
One spoon of regular sand on a petri dish per group.
One spoon of magic sand on a petri dish per group.
50ml of water.
2 x 100ml beakers.
During the enquiry (the extend stage), the materials depend on the research questions of the students. They may need different solvents: oil, acetone, ethanol, hexane, heptane (hydrophobic solvents which are allowed in school), soap, etc.
Exposing students to practical issues related to hydrophobic and hydrophilic interactions and compounds.