Got a warning like in_array() expects parameter 2 to be array, string given in
<div class="row">
<div class="col-sm-6">
<div class="form-group">
<label for="kids_age_range">AGe Range</label>
<div class="checkbox">
<label class="control-label" for="k_1_5">
<input type="checkbox" name="kids_age_range[]" value="1-5" id="k_1_5" {if in_array('1-5', $job.kids_age_range)} checked{/if} /> 1-5
</label>
</div>
</div>
</div>
</div>
If $job.kids_age_range is a single dimensional array you will need to cast the object into an array before you can use it.
// Cast to an array
$array = (array) $job.kids_age_range;