We’ve played with plenty of sensory bags in daylight, but this one is meant for after dark!
To set up, I poured a generous amount of baby oil into a large zip-top bag. Since we wanted to make two bags and I was out of baby oil, cooking oil worked in a pinch for the second bag. Squirt some glow-in-the-dark paint into each bag. Ideally I would have used watercolor paints, but even glow-in-the-dark fabric paint worked for this. Veronika absolutely loved the bright neon colors, even as we set this up during the day.
But the real fun came once the sun went down. You can simply look at the bags in the dark, but for added effect, I recommend switching on a black light. The kids were immediately squealing with delight at how the colors looked, so bright and glowing.
Encourage your kids to squish, squash, and watch how the bubbles of color move through the oil (a little bit like a lava lamp). If you have more than one color in each bag, as we did with a pink-and-blue version, see if the colors can mix together.
For sensory bag gets high marks for novelty.