Resposta - Validação de Nota Mínima

Classe Assessment:

namespace exercise79.Models;

internal class Assessment
{
    public string Student { get; set; }
    public double Grade { get; private set; }

    public Assessment(string student)
    {
        Student = student;
    }

    public void AssignGrade(double newGrade)
    {
        if (newGrade < 0 || newGrade > 10)
        {
            Console.WriteLine("Error: The grade must be between 0 and 10.");
        }
        else
        {
            Grade = newGrade;
        }
    }

    public override string ToString()
    {
        return $"Student: {Student} - Grade awarded: {Grade:F2}";
    }
}

Instância:

using exercise79.Models;

Assessment assessment = new Assessment("Carlos Eduardo");
assessment.AssignGrade(11);
assessment.AssignGrade(9);
Console.WriteLine(assessment);