At one point during the first week of class, Miss Honey asks Matilda to pay attention with everyone else: Miss Trunchbull will take over the class every week on Thursday afternoons. She does this with all classes. The children need to be clean, obey, and never make jokes. The children agree. Miss Honey says that Miss Trunchbull will probably test the children on the two-times table, so the children should practice tonight in preparation. There will also be a spelling test. And someone needs to volunteer to make sure that Miss Trunchbull’s jug of water and glass are on the table when she arrives. Lavender volunteers.
Again, Miss Honey is doing everything she thinks she can feasibly do to protect her charges from Miss Trunchbull. She feels as though she can warn them and prepare them to be quizzed by Miss Trunchbull—but she doesn’t seem to think she can get in Miss Trunchbull’s way. Through her actions, she shows that she believes the best way to deal with Miss Trunchbull is to do everything to avoid provoking her, and accept the abuse if it happens.
Lavender’s mind is spinning. She wants to be heroic like Hortensia, and Matilda has already told Lavender about stuffing the parrot in her parents’ chimney and bleaching her father’s hair. That afternoon, as Lavender walks home, Lavender hatches her plan. She picks her way down to the muddy pond in her garden, where a colony of ugly newts live. She scoops up a newt and carefully traps it in a pencil box lined with pond scum. Lavender carries the newt to school and though she wants to tell everyone, she knows she can’t—that way, nobody can rat her out if Miss Trunchbull tortures them.
Lavender’s thought process throughout this passage shows that she now thinks of herself as part of a close-knit underground resistance movement. She wants to be brave and crafty like Hortensia and Matilda, and she also wants to protect her idols and friends so nobody gets in trouble. And keep in mind that whatever Lavender is going to do with the newt, it probably won’t do any lasting damage. The point is more to show Miss Trunchbull that the kids can and will play tricks on her.
By the time lunch rolls around, Lavender is so nervous she can’t eat. When the meal is over, she races to the kitchen for one of the jugs. It’s a huge piece of pottery, which Lavender fills with water. Then, alone in the classroom, Lavender tips the newt into the jug, along with the pond scum. She puts her pencils back in her pencil box and rejoins her classmates on the playground.
Showing Lavender putting the newt into the water jug builds tension—readers and Lavender now expect that at some point, an unsuspecting Miss Trunchbull is going to discover the newt and be very unhappy. This lets readers in on the joke and lets them vicariously help torment Miss Trunchbull.