"The parents looked upon Matilda in particular as nothing more than a scab. A scab is something you have to put up with until the time comes when you can pick it off and flick it away." Chapter 1, pg. 6 (simile)
This metaphor aptly explains Matilda's parents feelings about her. They are not actively cruel towards her the way Miss Trunchbull is, but they simply tolerate her presence, clearly irritated by how different she is from them and unwilling to show her the love and affection they should. Eventually, the time does come when they "pick it off and flick it away." This happens when they allow Miss Honey to adopt Matilda, who shows her the love she never received from them.
"Miss Trunchbull never walked, she always marched like a storm-trooper with long strides and arms swinging." Chapter 7, pg. 51 (simile)
Dahl spends a lot of time describing Miss Trunchbull, allowing readers to get a clear picture of this terrible woman in their minds. The simile of Miss Trunchbull as a storm trooper makes it clear how rigid, large, and belligerent she is, three qualities that are central to her character and that will come into play repeatedly during the story.
"Her body was so slim and fragile one got the feeling that if she fell over she would smash into a thousand pieces, like a porcelain figure." Chapter 7, pg. 50 (simile)
This simile comes when Dahl is describing the way Miss Honey looks. Comparing her to a porcelain doll accentuates her delicacy and her outward beauty. It also sets her far apart from Miss Trunchbull, who is a "storm trooper." The two could not be more different, and the qualities that Dahl highlights about each of them make this fact clear.
"When at last the germ of a brilliant idea hit her, she began to expand on it and lay her plans with the same kind of care the Duke of Wellington had done before the Battle of Waterloo." Chapter 12, pg. 110 (simile)
As Lavender crafts her plan to put a newt in the Trunchbull's water glass, Dahl compares her actions to the Duke of Wellington, commanding a famous battle. This comparison raises the stakes, making sure readers take Lavender's efforts seriously. It also continues the metaphor of a full-blown war between the children and Miss Trunchbull, complete with battles and soldiers and weapons.
"She felt as though she had touched something that was not quite of this world, the highest point of the heavens, the farthest star." Chapter 20, pg. 187 (simile)
Dahl repeatedly describes Matilda's powers in terms of space and the heavens, making it clear that she is soaring far above the rest of the world in her mind when she uses them. This moment after she has the chalk write a message to Miss Trunchbull is particularly special, since she has succeeded in overcoming this beast once and for all, helping not only herself, but Miss Honey and the rest of the schoolchildren, too.
