Irregular bootstrap column wrapping

Running Rails 4.1.4 with the latest releases of haml, haml-rails, sass, and bootstrap-sass. For a user display, my HAML is as such:

.tutors-listing
    .row
      - @users.each do |tutor|
        .col-xs-12.col-md-3
          .row.tutor
            .col-xs-offset-1.col-xs-4.col-md-12
              = image_tag tutor.photo, :class => 'img-responsive img-circle tutor-photo'
              %h4.tutor-name
                = tutor.first_name

             %p
                teaches
             %strong.tutor-skills
               = tutor.teachables

However, this markup results in the following glitch:

I'm hoping somenone can devine what's wrong here. At the medium breakpoint, there should be 4 columns evenly.

This is caused by skills with 2 lines of text or more. It's a well-known bug when using float property. Here is a little picture to understand :

[Bootply] The issue

Option #1 : Force the height

Your first option is to force elements to have the same height :

.tutor {
    height: 500px;
}

• [Pro] Simple and work everywhere
• [Con] Use a magic number
• [Con] Limit the number of lines in skills
• [Con] Useless whitespaces on modile version

[Bootply] Force height

Option #2 : Use a clearfix

Your second option is to use a clearfix, and force the 5th element to be on a new line (same for the 9th, the 13th...) :

.tutors-listing > .row > .col-md-3:nth-child(4n+1) {
    clear: both;
}

• [Pro] Doesn't limit the number of lines in skills
• [Pro] No useless whitespaces
• [Pro] No magic number
• [Con] One CSS rule per size (xs/sm/md/lg)
• [Con] The rule depends of your grid (.col-xx-3)

[Bootply] Clearfix

In my case I wanted to show 3 items per row on large screens, 2 on medium screens, and 1 on smaller screens.

You may also uncomment the background colors to verify when the effect is triggering.

http://www.bootply.com/QOor73wFAY#

/* fixes for columns wrapping in odd ways due to variable height */
/* when showing 2 items per row, clear #1, 3, 5 */
@media (min-width: $screen-sm-min){
    .cell-box:nth-child(2n+1){
        clear: both;
        /* background-color: rgba(0, 0, 255, .5); /* blue */
    }
}
/* when showing 3 items per row, clear #1, 4, 7 */
@media (min-width: $screen-md-min){
    .cell-box:nth-child(2n+1){
        clear: none;
    }
    .cell-box:nth-child(3n+1){
        clear: both;
        /* background-color: rgba(0, 255, 0, .5); /* green */
    }
}

Sometimes, I run into this issue as well. I recommend trying to overwrite any padding or margin that you do NOT need. Try changing the margin to 0 first. Then remove some of the padding. That has helped in some of my cases.

By the looks of it you are rendering all of the columns in a single row. You need to change it so that it starts a new row every 4 columns i.e. (in plain old erb)

  <% @users.each_slice(4).to_a.each do |chunk| %>
     <div class="row">
       <% chunk.each do |tutors| %>
         <div class="col-sm-3">
           ...
         </div>
       <% end %>
    </div>
  <% end %>

You might not need the to_a on the first loop