1. Incorrect concept understanding: Some concepts in geometry are abstract, and students can easily understand deviations. For example, the definition of parallel lines is "on the same plane, two straight lines will never intersect", but some students may mistakenly think that as long as two straight lines do not intersect, they are parallel lines.

2. Calculation error: The calculation in geometry involves the measurement and calculation of angle and length, which is prone to calculation errors. For example, when calculating the area of a triangle, some students may forget to divide by 2 or reverse the base and height.

3. Graphics drawing error: Graphics in geometry need to be drawn accurately, but some students may draw the shape, size or position of the graphics incorrectly. For example, if you draw a square, some students may think that the lengths of the four sides are inconsistent or the angles of the four corners are incorrect.

4. Inference error: Reasoning in geometry requires strict logic, but some students may make logical errors. For example, when proving a theorem, some students may ignore the preconditions or use the wrong reasoning method.

5. Insufficient ability to solve applied problems: Some applied problems in geometry need to apply what they have learned to actual situations, but some students may lack this ability. For example, when solving a problem about distance, some students may not be able to apply the geometry knowledge they have learned to the actual distance calculation.

In order to avoid these mistakes, students should pay attention to the understanding of concepts, strengthen the accuracy of calculation, improve the drawing skills of graphics, cultivate strict logical thinking ability, do more practical application problems and improve their problem-solving ability.