Spelling lesson observation

I watched Shabnam teaching spelling with Leytia.

She was revising consonant blends and had written them on a chart like they were equations.

b+l=bl

c+l=cl

d+r=dr

s+t+r=str

s+c+r=scr

She defined blends as "2 or more consonants put together to make a new sound."

Shabnam then wrote up some letter combinations and asked the children "Is that a blend or not?"

The first one she put up was 'st.'
One child said it was and Shabnam restated "So you can hear the sound of the s and the sound of the t...is that what you're saying?"

She then put up "ch."  "Is that a blend?" she asked.  "Why or why not?"

Monisha said "You can't hear the c and the h."

She then put up "sh."  She got them to imagine putting the letters together.

She gave them "wh" and asked if the letters could be separated.  She gave Irma the word "whale" and asked if the w and the h could be separated in that word.  She then introduced the idea of digraphs.  "So if it's not a blend it's a digraph."
She shared the purpose of this new learning: "We are learning this so you'll be  able to use them in your writing.  Sometimes we have to sound things out but we can't.  So we just have to know them."