Where Do I Go Wrong?

Year 11, Language Disordered, ADD and acutely anxious.

For a term now we have been working on mastering the process of finding a percentage of a quantity.

First he does a sheet like this:

Change this percentage to a decimal.
23.5%

He moves the decimal place back two places and gets 0.235. He does 50 of these in around one minute now.

Next he does a sheet like this:

23.5% of 252.5

He converts to a decimal and puts the numbers into his calculator.
0.235 x 252.5
He does 50 of these in under 4 minutes.

Finally he does a sheet like this:

What is 23.5% of $252.50?

He has to convert the words to a number sentence
23.5% x $252.50
Change the percentage to a decimal
0.235 x $252.50
And put the numbers into the calculator.

Today was his 'exam'. He had three pages: 50 questions like the above on each page. He completed the first page. He mostly completed the second. He froze on the third.

After his exam time was up he came to me and told me he couldn't do the third page, they were just too confusing. He had no idea where to start.

"You've done these problems lots of times before." I protested.
"I don't care, I can't do them today. It's too confusing Mrs A. I don't know what I'm doing."
"But it's exactly the same process as the page before only this time it's in words..."
"I don't care, I can't do it. It's NOT the same. It's too confusing."

I explained the process again. I showed how the three sheets built up, one from the other using the same skills. I gave him another 15 minutes to complete the last page. At the end of the time he came to me and said "It's no use. I can't do them," and flounced away in a state of high anxiety.

What am I missing? Where has my process fallen down. Can someone please give me his perspective because I am at a loss!!!!!!

Still, on a positive note, at the beginning of term he couldn't even do 1 sheet of any type without asking for constant reassurance and asking questions every 30 secs. At least he got through the first two pages unaided today......

Oh. This young man has an average IQ by the way! He has what is called a Specific Learning Difficulty.