For my daughter’s last birthday, we had some of her friends for a sleepover party. Before bedtime, I wanted to use this opportunity to do something that only works after dark: A scavenger hunt in the dark.

In preparation, I requisitioned:

• A blacklight flash light
• A UV marker pen
• An infrared LED array
• A package of 100 glow-in-the-dark sticks
• A couple of flash lights and spare batteries

When the hunt began, we turned off all the lights in the house. Since the sun had already set quite some time ago, it was literally pitch black. Each kid got a flash light, and together they got the first clue: A scrambled message.

Just sorting out the message in the dim and flickering light of the flash lights was hilarious. The girls could barely keep their calm to sort out the message. Then came the tricks:

The infrared LED array – of which I forgot to take a picture, sorry – is something you can’t see with the naked eye. But a mobile phone camera can. So I gave them my phone, and they had to carefully scan the room, until a violet glow appeared on the screen, from the half-hidden LED array.

The UV marker pen was used to generously scatter hidden messages and visual cues around the house. These would light up from the blacklight flash light, like this:

For the finale, the girls had to solve a big scrambled message, complete with color-coded parts and UV parts, so they had to use both the blacklight and normal light for decoding:

The treasure included, among other things, copious amounts of glow sticks, which turned the whole thing into a frenzied neon dance:

I had some success with long-time exposure:

The scavenger hunt was a great success: The kids were incredibly excited, and just turning off the lights had a huge effect on the whole endeavor.

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