One group of items we could not find included roller balls and the Sharpie pen that came out of the backpack.
I said, "maybe they are hiding under the sofa cushions."
Perhaps that was an unfortunate turn of phrase, because it suggested to Mabel the idea of hiding under the sofa cushions herself.
She closed her eyes once she was settled – to complete her hiddenness. But the surface under the sofa cushions was "very bumpy" according to Mabel – so the experiment ended after only a short trial.