DIY: Arrow Reversal | Tinkerer Box Blog

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Arrow Reversal

Stem Activities

Ages: 3-5

Less than 30 minutes

Grownup needed

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Don't blink - you're about to witness 'magic' happening before your eyes! Why does the arrow change direction when water is added? This fascinating scientific phenomenon is actually related to light refraction.

Materials Needed

White paper
Marker pen
Glass
Water

Step-by-step tutorial

Step 1

Draw two arrows pointing in opposite directions on the white paper using the marker pen.

Step 2

Stand the paper with the arrows against a wall.

Step 3

Place the glass in front of the paper, ensuring you can see the arrows through it.

$An empty clear drinking glass sits on a light wood-grain table against a plain white background. Behind the glass, slightly out of focus, is a white piece of paper with a blue arrow pointing right and a red arrow pointing left, drawn one above the other. The glass refracts the image of the arrows, creating a distorted view of the directional symbols.$

Step 4

Pour water into the glass and carefully observe what happens to the arrows.

$A clear glass sits on a light wooden table with a piece of white paper positioned behind it. The paper features two arrows: a blue arrow pointing to the right and a red arrow pointing to the left. A hand pours water from a clear glass pitcher into the empty glass. As the glass fills, the arrows appear to change direction due to the refraction of light through the water. This video demonstrates a simple science experiment illustrating the principles of light refraction.$

The Science Behind It:

When light travels from one medium (like air) into another medium with a different density (like water), it changes direction. This is called light refraction. In this experiment, when water is poured into the glass, it alters the path of light rays, causing the arrows to appear "reversed". The water acts as a lens, bending the light and creating this optical illusion.

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