<%= form_for(@activity) do |f| %>
  <% if @activity.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@activity.errors.count, "error") %> prohibited this activity from being saved:</h2>

      <ul>
      <% @activity.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </div>

  <%= f.radio_button :polarity, Activity::NEUTRAL  %> 
  <%= label :polarity, "Neutral" %>
  <%= f.radio_button :polarity, Activity::POSITIVE %>
  <%= label :polarity, "+ Positive" %>
  <%= f.radio_button :polarity, Activity::NEGATIVE %>
  <%= label :polarity, "- Negative" %>

  <div class="actions">
    <%= f.submit %>
  </div>
<% end %>

<%= form_for(@activity) do |f| %>
  <% if @activity.errors.any? %>
    <div id="error_explanation">
      <h2><%= pluralize(@activity.errors.count, "error") %> prohibited this activity from being saved:</h2>

      <ul>
      <% @activity.errors.full_messages.each do |msg| %>
        <li><%= msg %></li>
      <% end %>
      </ul>
    </div>
  <% end %>

  <div class="field">
    <%= f.label :title %><br>
    <%= f.text_field :title %>
  </div>

  <div class="field">
    <%= f.label "This is activity is:" %><br>
    <%= f.radio_button :polarity, Activity::NEUTRAL  %> 
    <%= label :polarity, "Neutral" %>
    <%= f.radio_button :polarity, Activity::POSITIVE %>
    <%= label :polarity, "+ Positive" %>
    <%= f.radio_button :polarity, Activity::NEGATIVE %>
    <%= label :polarity, "- Negative" %>
  </div>

  <div class="actions">
    <%= f.submit %>
  </div>

  <br />

<% end %>

Add a label for the polarity radio buttons
Add a label for the polarity radio buttons
