Calculating the perimeter of different shapes, especially tricky ones like irregular polygons, can be hard for Year 7 students. Here are some common mistakes they make:

1. Wrong Side Measurements:

   • Sometimes, students don’t read or measure the sides correctly. This leads to wrong answers. About 30% of students say they mess up when measuring lengths.

2. Forgetting Sides:

   • With irregular shapes, students might forget to measure and add all the sides. Research shows that around 25% of students miss out on including every side, especially when the shapes look different.

3. Mixing Up Units:

   • A common mistake is using different measuring units (like centimeters and meters) in the same problem. Studies show that 15% of students run into trouble because they mix units.

4. Addition Mistakes:

   • Simple math errors can cause a lot of wrong perimeter calculations. Research suggests that 20% of mistakes happen because students add side lengths incorrectly.

5. Not Noticing Shape Features:

   • When students don’t recognize the special features of shapes, they might miss important details that help them find the perimeter. About 10% of students might misunderstand how to look at complex shapes.

By tackling these common mistakes, we can help students improve their skills and get better at calculating perimeters.