How to use multiple calls to getline() function

Question

#include <iostream>
using namespace std;

int main()
{
    string studentName;
    char grade;
    string teacherComment;

    cout << "Enter student name: ";
    getline(cin, studentName);
    cout << "Enter grade: ";
    cin >> grade;
    cout << studentName << " has received a grade of " <<grade<< endl;
    cout << "Enter comments: ";
    getline(cin, teacherComment);
}

I know the getline() function is used to get a string of text input from the user, but how come it won't work the second time? My program runs fine, it's just that it doesn't recognize the last line of code.