Step 1 — One score, one grade

void main() {
  int score = 85;
  if (score >= 90) {
    print('A');
  } else if (score >= 80) {
    print('B');
  } else if (score >= 70) {
    print('C');
  } else if (score >= 60) {
    print('D');
  } else {
    print('F');
  }
}

• Run and confirm output for 85 is B.
• Change score and run again for 95, 72, 55.

Step 2 — Use a variable for the grade

void main() {
  int score = 85;
  String grade;
  if (score >= 90) {
    grade = 'A';
  } else if (score >= 80) {
    grade = 'B';
  } else if (score >= 70) {
    grade = 'C';
  } else if (score >= 60) {
    grade = 'D';
  } else {
    grade = 'F';
  }
  print('Score: $score -> Grade: $grade');
}

• Use string interpolation $score and $grade in the print.

Step 3 — Add +/- (optional)

• For A: 93+ A, 90–92 A-.
• For B: 87+ B+, 83–86 B, 80–82 B-.
• Implement with nested or chained if/else and print the result.

Practice tasks

• Support scores 0–100 and handle invalid input (e.g. print "Invalid" for score < 0 or score > 100).
• Try the same logic with a switch on a numeric range (e.g. score ~/ 10) and compare with if/else.