Giving pupils a Picture Comprehension Assessment helps identify vocabulary and structures that need further reinforcement before progressing on to the next level of a reading scheme.

A crow and an owl

This pupil understands specific vocabulary

Two boys are in the park.  Ben has a black dog.  Paul has a black dog too.  Ben's dog is like Paul's dog.

This pupil shows understanding of 'like' to mean 'same' in this context.

"Watch me run Mum" said Ben.

This pupil doesn't understand the speech marks.  Questioning is needed to find out if they understand that it is Ben who is going to run.  If not - language input is needed on pronouns (me).

A shark under a boat.

This pupil self corrected when they re-read the text.

The seagull went up to the puppy.

This pupil needs language input on the meaning of 'up to' in this context.  It is a language need rather than a reading difficulty.