This is a spell to ASSIST (not replace) in studying for tests or reading comprehension. I wrote it and believe that it helped me greatly a few years ago when I needed to pass a licensing exam and waited until the very last minute to get down to business.
I am not big on elaborate setups or using a lot of supplies for spell casting. I believe that the true power of spells and magic come from within and from the caster's connection with the Earth/divinities. So this particular spell only requires three things: yourself, a true desire to succeed, and the books or papers that hold the information you need to retain.
Perform any preparatory ritual you may have, whether that be an invocation of your deities, drawing power down from the Moon or up from the Earth, etc. This spell invokes the Greek Goddess of Wisdom, Athena, but you can absolutely replace her with any other deity you associate with knowledge (the Greek God Apollo, the Roman Goddess Minerva, etc for example). Place your hands on the books or papers with the needed information, feel your energy rising from your core as it flows through your arms and into the pages. Envision and feel those strands of energy connecting with each page, each word, each letter and drawing them together into a singular orb of bright light as you speak this incantation:
"Goddess Athena, keeper and granter of knowledge, hear my call.
The task before me, I must not fail.
I come to thee in humbleness.
Bestow upon me your light so that I may see.
Give unto me your blessing so that I may persevere.
The knowledge held within these tomes must be in me,
And my mind and heart must be free from fear.
Let no question cloud my path,
Let no shadow blind me,
Let ignorance fall to your wrath,
And let wisdom be my key.
Work thy will, Goddess Athena and grant me this.
As above, so below.
By the power of three times three.
As you will it, so mote it be."
Feel that orb of energy pull together and condense into something brilliant and almost solid, then lift it and pull it into your core. Feel it spread throughout you.
Like I said, this is NOT A REPLACEMENT for studying. You should still do your very best as if you hadn't performed the spell, but if all is in your favor, this should greatly help you.
Best of luck and blessed be!