Setting up check-boxes side by side responsively using Bootstrap

I want to set up checkboxes side-by-side to visually represent something. It looks fine on my site but falls apart when trying to resize or on an iPad. I'm probably making a silly mistake but I would appreciate any corrections to my code.

http://ift.tt/1L8Q6Bl

<div class="col-md-6">
<div class="col md-6">
<div class="checkbox checkbox-primary">
<input id="checkbox1" type="checkbox" disabled="disabled" />
<label for="checkbox1">
Art
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" checked="checked" />
<label for="checkbox2">
Drama
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" checked="checked" />
<label for="checkbox3">
Foods and Nutrition
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" checked="checked" />
<label for="checkbox4">
Geography
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" checked="checked" />
<label for="checkbox5">
Industrial Arts/Shop Programs
</label>
</div>
</div>
</div>
<div class="col md-6">
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" />
<label for="checkbox6">
Math
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" />
<label for="checkbox6">
Music
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" checked="checked" />
<label for="checkbox6">
Technology
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" />
<label for="checkbox6">
Science
</label>
</div>
<div class="checkbox checkbox-success">
<input id="checkbox1" type="checkbox" disabled="disabled" />
<label for="checkbox6">
Physical Education/Health
</label>
</div>
</div>