It's a ready-resource to use in order to TEACH the dress-up you want to emphasize. I've photocopied the Hummingbird series, covering the "answer key" boxes in the margin, then let the child find and underline all the dress-ups--as a review. He can check his answers with the original to see if he found them all!
I've also used them as assignments for topic/clinchers. The child has to box the word in the topic and match it to its clincher in each paragraph using a yellow or pink highlighter.
Some of my co-op kids have had to mark all the sentence openers (then check it with the "answer key" in the original as homework). This is a great resource for a busy mom or co-op teacher because the child can check his own work, learning if he marked his right or not, which is direct reinforcement at the point of need. I love that! You can treat it like a "super sleuth" game, giving points for each one he finds! The Hummingbird set is very basic so each sentence opener is really obvious, granting success to kids who can easily identify them.
I've used them to illustrate Unit 4 research papers: We've identified the topics in each paragraph and made lists of possible topics for a paragraph or paper. It's easy to take notes from such resources.
Some Mini-Books include excellent examples of introductions and conclusions, or five-paragraph essays with three topics, even stylistic techniques like alliterations, VSSs or triple SSSs. Each series has special features.
They're a great link from single source research papers to the more complex Unit 6 multi-source papers. Kids can choose two or three Mini-Books, and a children's encyclopedia or library book as their third source, then take notes on typical topics. Each Mini-Book's opening sentence is designed to reveal the paragraph's topic (except for a few later ones which have "dramatic openings"!)
While the notes from the Mini-Books are easier to find, the library book or encyclopedia may be more difficult to use, but the child can still learn the process of using three sources for a research paper without too much stress from that more-difficult third source.
It's much easier to do than dumping ten library books in his lap and tossing 100 3x5 note-cards at him, expecting him to like writing research papers! (I didn't cry "buckets of tears" with such a daunting assignment when I was little, but I would have loved the seamless transition from mini-books to library books back then!)