Phase of the moon

The moon is second only to the sun as the most dynamic feature of our sky. It moves across the sky from east to west once every day and each month it goes from being invisible to the brightest object in the night sky and back to invisible again. These patterns result from the motions of the earth, moon and sun relative to each other.

Features of a wave

A standard set of terminology is used to describe the feature of waves.
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Boyle's Law

On Earth, naturally occurring matter exists in one of three phases: solid, liquid or gas. Matter in each phase exhibits distinct characteristics. Gases, for example, do not have a fixed volume or shape. As a result, gases respond to pressure changes by changing their volume. In other words, gases are compressible. In contrast, liquids and solids are not compressible. Their volume does not change in response to changing pressure. This is the reason air filled spaces in our ears “pop” during airplane takeoff and landings while the liquid filled spaces in our bodies do not. Boyle's Law describes this relationship between gas pressure and volume.

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Light reflection and refraction

Light is a complex phenomena. It exhibits both wave-like and particle-like properties and its exact nature is not completely understood. This complexity makes it difficult for one model to describe all of light’s properties. As a result, different models are used to describe different aspects of light’s behavior. The electromagnetic wave theory explains light’s ability to travel through a vacuum. The light ray model, on the other hand, can describe interactions between light and matter.
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Gravitational Acceleration

We all understand that if we hold something up in the air and then let go, it will fall to the ground. Things fall because of gravity. Gravity is an attractive force between all things that have mass.  It is one of the fundamental forces of nature. Gravity causes objects with mass to accelerate towards each other. The rate of acceleration depends on the mass of the objects and their proximity. The more mass an object contains, the more it will attract other objects. The closer an object is to another the greater the attraction between them will be.
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Punnett Square

During sexual reproduction, a parent is equally likely to pass on to its offspring either of the two alleles it has at each genetic locus. This makes it possible to list and estimate the probability of specific genotypes being produced from the pairing of two individuals. Given two allele from each parent, four allele combinations are possible. These combinations and their probabilities can be readily visualized using a Punnett square.
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Buoyancy

Why do some things float and others sink? The first thing that comes to mind for many people is that it depends on how heavy an object is. While an object's weight, or more properly its mass^* does play a role, it is not the only factor. If it were, we could not explain how a giant ocean liner floats while a small pebble sinks. Mass matters, but there is more to it.
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