Because I do not know the context of what is "cool," I am going to assume that is referring to the weather/temperature.
In Spanish, we use the verb "hacer" in expressions that refer to weather conditions.
The direct translation of "It is cool," is:
Hace fresco.
We use the third singular form of the verb hacer because we are talking about the weather.
1.) Los niños so bajos.
2.) Los niños so altos.
3.) Los niños son altos.
4.)Los niños son inteligentes.
All of the sentences have something incorrect some forget the tilde and some have misspelled words. This is how all the sentence should look if they were correct.
