function get_content() {
        if ($this->content !== NULL) {
            return $this->content;
        }

        if (empty($this->instance)) {
            $this->content = '';
            return $this->content;
        }

        $this->content = new stdClass;
        $this->content->text = '';
        $this->content->footer = '';

        $renderer = $this->page->get_renderer('block_recent_activity');
        $this->content->text = $renderer->recent_activity($this->page->course,
                $this->get_timestart(),
                $this->get_recent_enrolments(),
                $this->get_structural_changes(),
                $this->get_modules_recent_activity());

        return $this->content;
    }