Thank you for showing me new ways that my
books do not show.

This is very interesting!
Thank you!

Grades and cutoffs in tables are good, but also that can be tidied up.
IMO there's too much innecessary duplicate code in if-elses. How about
something like this:

public class Grade {

   public static final String[] grades = { "A+", "A", "A-", "B+", "B",
       "B-", "C+", "C", "C-", "D+", "D", "D-", "F",  };
   public static final int[] cutoffs =       { 96,    92,   90,    86,
       82,  80,    76,    72,   70,   66,    62,   60,   };

   /** static method to get grade-string corresponding to given points.
    * @throws IllegalArgumentException if points outside 0-100 */
   public static String getGradeString(int points) {
       // check that points is legal
       if (points < 0 || points > 100) throw new IllegalArgumentException("Illegal points, must be
within 0 and 100");
       // get grade-string by iterating through cutoffs
       String gradeString = grades[grades.length-1]; // init to "F"
       for (int i=0; i<cutoffs.length; i++) {
           if (points >= cutoffs[i]) {
               gradeString = grades[i];
               break; // found correct grade, abort loop
           }
       }
       return gradeString;
   }

   // testing..
   public static void main(String[] args) {
       //System.out.println(Grade.getGrade(101).getGrade()); throws exception
       System.out.println(Grade.getGradeString(100));
       System.out.println(Grade.getGradeString(96));
       System.out.println(Grade.getGradeString(72));
       System.out.println(Grade.getGradeString(60));
       System.out.println(Grade.getGradeString(59));
       //System.out.println(Grade.getGrade(-1).getGrade()); throws exception
   }

}

Grades could also be thought as objects, then the class could look
something like this:

public class Grade {

   public static final String[] grades = { "A+", "A", "A-", "B+", "B",
       "B-", "C+", "C", "C-", "D+", "D", "D-", "F",  };
   public static final int[] cutoffs =       { 96,    92,   90,    86,
       82,  80,    76,    72,   70,   66,    62,   60,   };

   // private fields
   private String grade;
   private int points;

   /** constructor is not accessible outside Grade-class, you must use
    * static getGrade-method to get Grade-object */
   private Grade(String grade, int points) {
       this.grade = grade;
       this.points = points;
   }

   /** static method to get Grade-object corresponding to given points.
    * throws exception if points outside 0-100 */
   public static Grade getGrade(int points) {
       String gradeString = getGradeString(points);
       // create new Grade-object with grade-string and points-integer
       Grade grade = new Grade(gradeString, points);
       // return grade-object
       return grade;
   }

   /** static method to get grade-string corresponding to given points.
    * throws exception if points outside 0-100 */
   private static String getGradeString(int points) {
       // check that points is legal
       if (points < 0 || points > 100) throw new IllegalArgumentException("Illegal points, must be
within 0 and 100");
       // get right grade-string by iterating through cutoffs
       String gradeString = grades[grades.length-1]; // init to "F"
       for (int i=0; i<cutoffs.length; i++) {
           if (points >= cutoffs[i]) {
               gradeString = grades[i];
               break;
           }
       }
       return gradeString;
   }

   /** accessor for grade-field */
   public String getGrade() {
       return grade;
   }

   /** accessor for points-field */
   public int getPoints() {
       return points;
   }

   /** Returns a string representation of the object. */
   public String toString() {
       return grade;
   }

   // testing..
   public static void main(String[] args) {
       //System.out.println(Grade.getGrade(101).getGrade()); throws exception
       System.out.println(Grade.getGrade(100));
       System.out.println(Grade.getGrade(96));
       System.out.println(Grade.getGrade(72));
       System.out.println(Grade.getGrade(60));
       System.out.println(Grade.getGrade(59));
       //System.out.println(Grade.getGrade(-1).getGrade()); throws exception
   }

}