The sand has a lower density, so the sand is water-permeable. The sand particles are not bonded to each other, there is a lot of free space, so water passes through it easily. The density of clay is much higher, therefore, water passes through the clay more difficult. That is why earthenware was created in which you can cook food and draw water.
One of the components of a person's success in our time is receiving modern high-quality education, mastering the knowledge, skills and abilities necessary for life in society. A person today needs to study almost all his life, mastering everything new and new, acquiring the necessary professional qualities.