It's something completely different: Elly being martyred because Lizzie doesn't know what things are for.
Panel 1: As John passes a wailing Lizzie to Elly in a manner that somehow scares the crap out of me, she asks her what's wrong; he says that Mike was showing him his school supplies and she feels left out.
Panel 2: She tells John and Lizzie that she has school supplies for her too: paper and colored pencils and all sorts of things. Lynn's attempt to tell us that Elly did think to include Lizzie after all, so there, nyahhhhh, you picky-faces is subverted by the fact that Mike and Liz were watching her buy everything. Unless, of course, she went for a second run because she just realized why Lizzie was yelling 'Want that' all the time and took a second trip.
Panel 3: Elly "asks" her if she would like pencils in such a manner that suggests that she actually means to say "Here are some pencils to play with"; Lizzie SHREIKS with misspelled delight.
Panel 4: Elly smiles as she says that Lizzie can have paper and pencils.
Panel 5: Elly is gobsmacked as Lizzie tries to EAT the pencils; apparently, no one forwarded her the memo that reminds us that children that small will tend to try to jam any old thing in their mouths.
Summary: The premise, of course, is that despite trying her best to be responsible, Elly is stuck with children who do silly, strange and baffling things; this is sort of spoiled by the fact that she never learns to expect the unexpected.