Controller

def edit_measurements
      @estimate = Estimate.find(params[:id])
      @measurements = @estimate.measurements 
    end
  
    def update_measurements
      #Find object using form parameters
      @estimate = Estimate.find(params[:id])
      #Update subject
      if @estimate.update_attributes(params[:estimate])
        #if save succeeds, redirect to list action
        redirect_to(:action => 'list_current')
      else
        #if save fails, redisplay form to user can fix problems
        render('edit')
      end
    end

form

<div>
  
	<h2>Measurements For: <%= @estimate.project.name %></h2>
	
	<%= form_for @estimate, :url => {:action => 'update_measurements', :id => @estimate.id} do |f| %>
	
	<table summary="Lead detail view">
		
		<%= f.fields_for :measurements do |m| %>
		<tr>
			<th><%= m.text_field(:name) %></th>
			<td><%= m.text_field(:amount) %>
		</tr>
		<% end %>
	</table>
	<%= f.submit "Submit" %>
	<% end %>
</div>