When to use ReactiveDict vs ReactiveVar - meteor

Question

I'm in Meteor and have been using Reactive Var in my project with no issues. In this current example I'm not sure if I need to use a ReactiveDict instead because I'm getting no reactivity with ReactiveVar.
I'm setting the value of the reactiveVar to a mongo query that is resulting in an array of objects.
Template.MasterList.onCreated(function () {
this.teacherList = new ReactiveVar('');
});
Template.MasterList.onRendered(function () {
var weekNum = Session.get('CurrentWeek').substr(0, 1);
var week = 'Week' + weekNum;
var query1 = {};
query1[week] = { $in: ['JC', 'JF', 'F']};
this.teacherList.set(Programs.find({ $and: [{ CampYear: Session.get('GlobalCurrentCampYear') }, query1]}, { sort: { FullName: 1 }}).fetch());
});
One object in the array would look like:
{ ...
Students: {
Week1: {
Monday: ['Joe', 'Mary']
},
Week2: {},
Week3: {}
}
...
}
One of the objects in the array may change to something like:
{ ...
Students: {
Week1: {
Monday: ['Joe', 'Mary', 'Bill']
},
Week2: {},
Week3: {}
}
...
}
When a change to one of the objects happens, the reactiveVar doesn't see the change in the array to re-fire the helper. Is a ReactiveDict to be used here instead?
EDIT:
Helper function:
saturdayTeacher: function (name) {
var weekNum = Session.get('CurrentWeek').substr(0, 1);
var week = 'Week' + weekNum;
var teachers = Template.instance().teacherList.get();
for (var i = 0, len = teachers.length; i < len; i++) {
if (_.contains(teachers[i].Students[week].Saturday, name)) {
Meteor.defer(function () {
i = 0;
});
var teacher = teachers[i].FullName.split(' ');
return teacher[0] + " " + teacher[1].slice(0, 1);
}
}
},

Answer 1

What will help you in a very easy way, is to add an autorun to your onRendered-Function, where you set your ReactiveVar. Because the onRendered-Function is only executed once. When I get it right, you want to listen on changes in the cursor, Session.get('CurrentWeek') and Session.get('GlobalCurrentCampYear').
So try this:
Template.MasterList.onRendered(function () {
var self = this;
this.autorun(function() {
var weekNum = Session.get('CurrentWeek').substr(0, 1);
var week = 'Week' + weekNum;
var query1 = {};
query1[week] = { $in: ['JC', 'JF', 'F']};
self.teacherList.set(Programs.find({ $and: [{ CampYear: Session.get('GlobalCurrentCampYear') }, query1]}, { sort: { FullName: 1 }}).fetch());
});
});
Than it will be executed all the time the result of the query or the Session-Values change.