Dyslexia testing - how do they decide to test?

[ShiftyFades]

I had a letter in DSs bag saying they'd be doing a dyslexia test on "some" children this term. I've asked 2 other mums if they had the leaflet, they didn't. So it's definitely been a selection of children (or just mine?!!)
I'm really gutted they didn't talk to me and just shoved a letter in. I think DS is fine. He's only in reception and recognises letters and is grasping phonics. I'm actually pleased at the process, I think it's been amazing.
Obviously I am wrong and something is going on

He's in breakfast and after school club now until I pick him up on Friday, so I think it's pretty mean to not have spoken to me about this letter.

I'm quite upset
What shall I do? Ring the school and ask for the teacher to ring me? Or wait until Friday?

For what is worth, my daughter reads well but struggles with spelling. She has no memory for spelling and even though her spelling makes sense it is phoneticly wrong. One example is that she can read saw and was but she needs to think a little if she has to write it down since these two words have the same letters in different order.

One example is that she can read saw and was but she needs to think a little if she has to write it down since these two words have the same letters in different order.

That's interesting. Is she trying to recall spellings by what the words 'look' like?

Can she not write the sounds in the order in which they come in the words?

She can write correctly if she says out loud.
She also put lots of y when she should use u, f for th and so on

She struggles with the sounds and recalling how to use phonics in writing.