Four students are developing a model to illustrate covalent and ionic substances dissolving in
water. They each write down what they think is the most important difference between
covalent and ionic compounds dissolving in water. Which student has the best understanding
of what the model needs to illustrate?

The students with ionic bonds have a better understanding of what the model needs to illustrate.

Explanation:

When ionic compounds dissolve in water, they break apart into the ions that make them up through a process called dissociation. When placed in water, the ions are attracted to the water molecules, each of which carries a polar charge. If the force between the ions and the water molecules is strong enough to break the bonds between the ions, the compound dissolves. The ions dissociate and disperse in solution, each ringed by water molecules to prevent reattachment. The ionic solution turns into an electrolyte, meaning it can conduct electricity.While covalent compounds dissolve in water they break apart into molecules, but not individual atoms. Water is a polar solvent, but covalent compounds are usually nonpolar. This means covalent compounds typically don't dissolve in water, instead making a separate layer on the water's surface.

The  grandmother cell  is a hypothetical  neuronthat represents a complex but specific concept or object.[1]  it activates when a person "sees, hears, or otherwise sensibly discriminates"[2]  a specific entity, such as his or her grandmother. the term was in use at least as early as 1966 amongst staff and students in the department of experimental psychology, university of cambridge, england. a similar concept, that of the  gnostic neuron, was proposed two years later

High-energy and unstable.