The concept of proportion refers to the corresponding relationship between two numbers, which can be used to express the quantitative relationship between projects. To simplify the ratio, we must reduce the same factor in two ratios to get the simplest ratio. The simplified ratio is more concise and easy to calculate and use. In real life, proportion is widely used in various calculations and descriptions, such as various miniature car models.
Multiply or divide one of the two ratios by a number to get a new ratio. This process is called enlargement or reduction. In plane geometry, the length of a line segment can also be expressed in proportion. The numerical value in the scale usually represents the length of the line segment, and the simplification, enlargement and reduction of the scale also apply to the line segment.
Proportional learning difficulties
1, calculation of continuous proportion: sometimes a whole is divided into several parts and is proportional to other items. This requires the calculation method of continuous proportion, which may be difficult for beginners.
2. Application of proportion: proportion is widely used in real life, but sometimes the topic needs to be combined with other mathematical knowledge points (such as area and volume) to calculate proportion, which may require students to have certain logical thinking ability.
3. Accuracy: In the proportional calculation, it is necessary to ensure the accuracy of the results. But in practice, there may be errors, which requires students to have strong calculation and estimation ability.
4. Graphic scale and ruler drawing: In addition to line scale, graphic scale and ruler drawing are also important applications of scale. However, this requires students to master more geometric knowledge and the ability to judge graphics.