Show a page with child Terms when parent Term clicked in block?
Try the Views tree module. It is great for taxonomy trees.

This module provides a tree-based style plugin for Views. It is equivalent to the tree-based style template from Views 1.
It is based off of the list style. Although it generates a nested view, there is still only a single query run for the view making it quite performant.

There is also a patch for adding collapsible support but I'm not sure how complete it is. See http://drupal.org/node/1538414