Mathematical olympiad in primary schools usually does not involve complicated mathematical theories and formulas, but we can briefly introduce the butterfly theorem (in fact, it is the butterfly effect). Butterfly theorem is a concept in chaos theory, which means a small change that may have a great impact in the long run. Specifically, it describes that small changes in initial conditions may have a great impact on the evolution of dynamic systems.

Although the butterfly theorem involves relatively complex mathematical theories and equations, as a primary school olympiad, we can understand and discuss this concept in simple terms.

We can illustrate the concept of butterfly theorem through a simple example. Suppose we have a rope that is one meter long and can swing. We can lift the rope manually and swing in the air. If we gently lift the rope with a smile and let it swing in the initial condition, the swing amplitude may be small.

However, if we change the initial conditions slightly, such as smiling into laughing loudly, or changing the height of our hands, we will find that the amplitude of the rope swing is different. This slight change may lead to a change in the trajectory of the rope and eventually produce different results.

This is a simple explanation of the butterfly theorem. Although specific formulas and derivations will not be involved in primary school olympiad, we can understand the basic concept of butterfly theorem through this example. Simply put, the butterfly theorem tells us that small changes may have a great impact in the long run.

Butterfly theorem is a concept in mathematics, which belongs to a higher level of mathematics, and is generally not involved in elementary school olympiad. Primary school olympiad usually focuses on cultivating students' basic mathematical thinking and problem-solving ability, including basic concepts and calculation methods such as integer, decimal, fraction and geometry.

The following are some common formulas and concepts in primary school olympiad:

1. area formula:

Square area formula: side length × side length

The area formula of rectangle: length × width

The area formula of triangle: base × height /2.

2. Perimeter formula:

The perimeter formula of a square is 4× side length.

Rectangular perimeter formula: 2× (length+width)

The perimeter formula of triangle: side 1+ side 2+ side 3.

3. Volume formula:

Cubic volume formula: side length × side length× side length.

The cuboid's volume formula: length × width × height.