You want your Class VI students to figure out that the property of solubility of salt in water can be used to separate a mixture of sand and salt. As a supporter of inquiry- oriented pedagogy, you would

explain different methods of separation of mixtures first and then explain the separation of sand and salt mixture

provide the mixture of sand and salt to students, ask them to think up different ways of separation and help them in trying out their ideas

ask students to hypothesise about different ways in which a mixture of sand and salt can be separated and then lead them to the correct answer through detailed explanations

take a mixture of sand and salt, demonstrate its separation and then ask students to repeat it on their own