I would like to add a simple area calculator form (length x width x depth = area) to a sidebar block, and I'm having problems figuring how to get the form to show up in the block using hook_block().  I've gotten the block to show up in the blocks list and have enabled it, but I can't get it to show up.  I've been using the blocks chapter in the PDD book as a guideline, but I must be missing something.

Here's what I have so far.

<?php

function calculate_square_form() {
    $form['length'] = array(
        '#title' => t('Length'),
        '#type' => 'textfield',
        );
       
    $form['width'] = array(
        '#title' => t('Width'),
        '#type' => 'textfield',
        );       

    $form['depth'] = array(
        '#title' => t('Depth'),
        '#type' => 'textfield',
        );
       
    $form['length'] = array(
        '#type' => 'button',
        '#value' => t('Calculate area')
        );
}       

function shbark_calculate_block($op = 'list', $delta = 0, $edit = array()) {
    switch ($op) {
        case 'list':
            $blocks[0]['info'] = t('Square area calculator');
            return $blocks;
           
        case 'view':
            $block['subject'] = t('Area calcultor');
            drupal_get_form('calculate_square_form');
            break;
    }
}
    
How do I get my block content to be displayed?  Do I have to pass the form to a theme function?  Do I assign the form data to $block['content'] somehow?  Or do I have to put the form array in the 'view' case for $op instead of a separate form function?

Thanks.

Steve