A teacher maintains a database containing two tables–Students and Grades.  The Students table has three fields: studentID, lastName and firstName.  The Grades table has four fields: studentID, firstExam, secondExam, and finalExam.  At the beginning of the semester, the Students table is filled in completely with a record for each student in a class, and the Grades table has a record for each student that contains only the student’s ID number. (Note: The database is contained in the file Gradebook.accdb). Using Visual Basic write a program that allows the instructor to record and process the grades for the semester.  The program should do the following:

1. Use a navigation toolbar to fill the Grades table.
2. After all grades have been entered, display a DataGridView control showing the name of each student and his or her semester average.  The semester average should be calculated as (firstExam + secondExam + 2 * finalExam) / 4.  See the figure below.

Suggested Control Names and Attributes:

Name Property	Text Property	Control Type	Notes
frmGradeBook	Grade Book	Form	Holds Controls
txtID		TextBox	Capture student ID
txtExam1		TextBox	Captures score for exam 1
txtExam2		TextBox	Captures score for exam 2
txtFinal		TextBox	Captures score for final
btnDisplay	Display Student Grades	Button	Triggers event to display data
dgvOutput		DataGridView	Displays data