Step 2 : Increase the number of pictures and get Rayyan to match them, one by one.
Step 3 : Place two pictures on a table and instead of giving him pictures to match, give him words instead, one at a time.
Step 4 : Increase the number of pictures and get Rayyan to match the words to the pictures, one by one.
Step 5 : Place a couple of pictures on a table and give Rayyan the whole stack of pictures to match, then the words.
He's good at the matching game :)