Logig in CFGRID / CFGRIDCOLUMN

Oh, and, you may of course use switch-case in place of if-else.

<cfset students = "Student 1,Student 2,Student 3,Student 4,Student 5">
<cfset Grade_Numbers = "90,98,80,75,60">

<cfform name="GradesForm" format="flash">
<cfgrid name="gradeGrid" height = "120" onChange="getGradeLetter();">
<cfgridcolumn name="student" header="Student Name">
<cfgridcolumn name="gradeNumber" header="Grade Number">
<cfgridcolumn name="gradeLetter" header="Grade Letter">
<cfloop index="i" from="1" to="#ListLen(students)#">
<cfgridrow data ="#ListGetAt(students, i)#,#ListGetAt(Grade_Numbers, i)#,">
</cfloop>
</cfgrid>
<cfformitem type="script">

function getGradeLetter(){
var gradeNumber = parseInt(gradeGrid.selectedItem.gradeNumber);
if(gradeNumber >= 90 && gradeNumber <= 100) {
gradeGrid.selectedItem.gradeLetter = "A";
}
else if(gradeNumber >= 80 && gradeNumber < 90) {
gradeGrid.selectedItem.gradeLetter = "B";
}
else if(gradeNumber >= 70 && gradeNumber < 80) {
gradeGrid.selectedItem.gradeLetter = "C";
}
else if(gradeNumber >= 60 && gradeNumber < 70) {
gradeGrid.selectedItem.gradeLetter = "D";
}
else {
gradeGrid.selectedItem.gradeLetter = "F";
}
}
</cfformitem>
</cfform>