The first stage of mitosis called prophase

In this video, I answer the question, " What makes an insect an insect?
An insect belongs to the phylum Arthropoda and the class Insecta
Insects have an exoskeleton,wings,6 legs, and a segmented body.

Ecological pyramids
Ecological pyramids show how energy is transferred in an ecosystem.
In this video, I cover three types,
pyramid of energy
pyramid of biomass
pyramid of numbers

In this video, I describe the four stages of mitosis, prophase, metaphase, anaphase, and telophase.
During metaphase, the sister chromatids align in the middle of the cell.
However for this to happen a couple of things had to happen during prophase
During prophase, the chromatin condensed into x shaped chromosomes.
Each half of the x is a sister chromatin with identical copies of the DNA
In other words, a sister chromatin is 'one-half' of the duplicated chromosome.
The two sides of the x shaped chromosome is attached at the centromere.
Centromeres are the regions of DNA where the sister chromatids are most tightly connected.
During anaphase, the chromosomes line up in the middle of the cell.
The chromosomes move away from each other during the phase of mitosis called anaphase.
Finally, in telophase, the nuclear membrane reappears and the cell pinches in the middle.

A concave mirror curves inward in the center. In this video, I use a laser to demonstrate ray of incidence, the ray of reflection,focal point,center of curvature, and the vertex

The Equinox is the date in which the day and night are equal. The Solstice is the longest day of the year? Because the Earth is tilted at a 23.5 degrees angle and also rotates and revolves around the earth the length of the day varies though out the year
During each equinox, both hemispheres receive almost equal amounts of sunlight
12 hours of daylight and 12 hours of nighttime.
Questions answered in this video?
What are the dates of the vernal equinox and the autumn equinox?
What are the dates of the summer solstice and the winter solstice?
What is the equilux?
When is the shortest day of the year?
When is the longest day of the year?

Have you ever wondered how you catch a cold? I discuss 5 ways microorganisms spread.
These include direct contact, indirect contact, airborne, oral route, insects and pests.

Learn how to create a stem and leaf plot. A stem and leaf plot is another method for organizing data so you can see patterns.
Draw the Stem and Leaf Chart
Identify the Stem
Sort your data and divide the numbers into a stem and a leaf
Provide a key

Mountain and Valley Breezes occur when the slopes of the mountain and the valley heat up and cool off at different rates. Valley breezes occur during the day and mountain breezes occur at night.

Learn the basics of Lichen and Moss. In many places on Earth, you will find Lichen and Moss living beside each other. Although they may look similar they are very different. Lichen are actually a symbiotic relationship between fungi and cyanobacteria. Moss are nonvascular plants.

When telling time there are different ways you can tell someone what time it is.
For example, when the small hand is on the three and the large hand is on the five could be called 3:05 o five past three.
In this video, I go over common phrases used when telling time.

Diffraction is the bending of light as it passes around the edge of an object or through a slit.
Refraction is the bending of a wave when it enters a medium where its speed is different.
When a wave passes through a slit it spreads out in waves as it passes through the slit.