Ember not showing foreign key field data

I have four models

//models/exam.js

name: attr('string'),
owner: belongsTo('user'),


//models/question.js

content: attr('string'),
exam: belongsTo('exam')


//models/answer.js

owner: belongsTo('user'),
question: belongsTo('question'),
answer: attr('string'),
remarks: attr('string'),
exam: belongsTo('exam')


//models/user.js

owner: belongsTo('user'),
question: belongsTo('question'),
answer: attr('string'),
remarks: attr('string'),
exam: belongsTo('exam')

I load the models into a route. Then, when I run the following template code,

<p></p>

it shows the output as follows

<frontend@model:question::ember276:5>
<frontend@model:question::ember281:6>
<frontend@model:question::ember286:4>

why is it showing such an code, why not showning the original content?