Science
A force is a push or a pull on an object.
A force changes the motion of a moving object.
A force can be strong or weak, and it always has a direction.
The Earth is a planet that goes around the sun in a circular orbit (圆周轨道，圆形轨道).
The speed of its motion doesn't change, but the direction of its motion does.
The Earth has a layer of gas above its surface, which helps to support life.
Atoms are the building blocks (积木) of matter.
At the center of an atom is its nucleus (核心), which has a positive electric charge (正电荷).
Outside the nucleus are electrons (电子), which have a negative charge (负电荷).
Asteroids (小行星) and comets (彗星) are objects that orbit (绕…轨道而行) our sun but are smaller than planets.
Asteroids that pass close to the Earth are called near-earth objects (近地目标星体，近地物体).
The layer of gases just above Earth's surface is our atmosphere (大气层).
The atmosphere is made up of gases, such as oxygen and nitrogen (氮).
Without an atmosphere, there would be no life on Earth.
Exercise:
1.— What changes the motion of a moving object?
— A force changes the motion of a moving object.
2. —What is the layer of gases just above Earth's surface?
— The layer of gases just above Earth's surface is our atmosphere.
3.— What has a nucleus and an electrons?
— Matter has a positive charge nucleus and a negative charge electrons.
4.— What objects orbit our sun but are smaller than planets?
— Asteroids and comets are objects that orbit our sun but are smaller than planets.
5.— What keeps the Earth in an orbit around the sun?
— It moves in an orbit around the sun because of the gravitational force between them.
6. A force can increase or decrease the speed of an object, and it can change the direction of motion.
7. The electric force between the nucleus and electrons holds the atom together.
8. Asteroids that pass close to the Earth are called near-earth objects.
Repeat & Read Sentences:
1. A force is a push or a pull on an object.
2. Without an atmosphere, there would be no life on Earth.
3. The Earth has a layer of gas above its surface, which helps to support life.
4. At the center of an atom is its nucleus, which has a positive electric charge.
Geometry
The two lines on the left intersect each other at a right angle, which is 90 degrees.
The two lines on the right are parallel, which means they never cross.
The adjacent (相邻的，邻近的) sides of a rectangle are perpendicular (垂直的), which means they meet at a 90-degree angle.
The opposite sides of a rectangle are equal and parallel, which means they never cross.
The area of a rectangle is the length times the width.
A circle is a two dimensional figure (二维图形，平面图形) with a radius and circumference (周长), which is the distance around the circle.
The area of a circle is pi r squared, where r is the radius and pi is the ratio of a circle's circumference to its diameter.
A sphere is a three dimensional figure (三维图形，立体图形) with a radius and a volume, which is 4/3 pi r cubed.
All points on the surface of a sphere are equidistant from its center.
A right triangle (直角三角形) is a two dimensional figure with 3 sides, two of which are perpendicular.
To find its area, multiply the lengths of the two perpendicular sides, a and b, and divided by two. A = 1/2 ab.
Exercise:
1.— Which two lines intersect at a right angle?
— These two lines intersect each other at a right angle, which is 90 degrees.
2.— Which two dimensional figure has a radius and circumference?
— A circle is a two dimensional figure with a radius and circumference, which is the distance around the circle.
3.— Which two dimensional figure has four sides?
— A rectangle is a two dimensional figure with four sides.
4.— Which three dimensional figure has a volume which is 4/3 pi r cubed?
— A sphere is a three dimensional figurewith a radius and a volume, which is 4/3 pi r cubed.
5.— Which two dimensional figure has three sides?
— A right triangle is a two dimensional figure with 3 sides, two of which are perpendicular.
6. The two lines on the left intersect each other at a right angle, which is 90 degrees.
7. The opposite sides of a rectangle are equal and parallel, which means they never cross.
Repeat & Read Sentences:
1. A rectangle is a two dimensional figure has four sides.
2. Pi is the ratio of a circle's circumference to its diameter.
3. All points on the surface of a sphere are equidistant from its center.
4. The opposite sides of a rectangle are equal and parallel, which means they never cross.
