Fencing paddocks
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Overview
Using this Resource
Connecting to the Curriculum
Marking Student Responses
Working with Students
Further Resources
This task is about calculating the length of fencing needed around three paddocks.
A farmer has three paddocks to fence.
Each paddock is shown with the length of its sides
Task administration:
This task can be completed online and has auto marking displayed to students.
Level:
4
Curriculum info:
Description of task:
Students are asked to work out the perimeter of different polygon shapes.
Curriculum Links:
This resource can help to identify students' understanding of calculating length and perimeter of shapes.
Learning Progression Frameworks
This resource can provide evidence of learning associated with within the Mathematics Learning Progressions Frameworks.
Read more about the Learning Progressions Frameworks.Answers/responses:
| Y8 (11/2015) | ||
| a) | 68 | very easy |
| b) | 84 | easy |
| c) | 106 | difficult |
| All 3 correct | difficult | |
Results based on 100 Year 8 students.
Teaching and learning:
This task is about calculating perimeters. It involves working out side lengths not explicitly indicated, and then calculating the total perimeter for a number of different shapes.
NOTE: As the perimeter is illustrated in the context of fencing, this task does not identify whether students can distinguish perimeter from area. To address this use assessment resources such as Area and perimeter and Finding area and perimeter.
Diagnostic and formative information:
Some students exhibited a range of errors that involved calculation, scribing, and missing sides.
| Common errors | ||
| a) | 58 | Calculation error - Student drops one of the tens in calculation |
| a) | 66 | Scribing error - Student either drops the 2 from 22 (or 12) or adds 12 instead of 14 |
| c) |
83
77 |
Missing a side error
This error is more common in question c) as it is a more complex shape with more implicit measures of length that students have to work out.
- missing the 23m horizontal top length
- using 15m for the left vertical side and missing the 23m top horizontal length.
|
Next steps:
For students who exhibited the three types of errors: calculation, scribing, and missing sides checking over their answers is a first step to ensure that they think they have provided a complete and accurate solution. An intermediary step for questions b) and c) could be to simply label the length of the missing sides. If printing the resource helps, students could do this and write on the sheet, to mark off sides, and then show their strategy for adding the lengths. They could then check this with a peer or a calculator.
The error involving missing sides could involve getting students to explain how they organise solving the problem. Ensure that students have some sort of system that checks that they have included all sides in the calculation. For example, do they work clockwise from a point? count off the number of sides for each length added? or calculate the shown lengths and then those implied? Some organisational strategies are more robust than others. Possibly, reverting to writing down may help, e.g., having a notebook in which students can make notes, draw diagram or write measures.
- Calculating the perimeter
- Finding area and perimeter
- Measuring the extension
- How big is the community hall?
- Finding the perimeter
- Fencing the field
- Using string lines
- Using cubes
- Garden perimeter
- Making road signs
- Changing perimeter
- Area of 3 fields
- Same area, different lengths
- Smallest perimeter
- Making the largest perimeter
- Area and perimeter of four shapes
- Correcting mistakes
- Perimeter and length
- Extending the garden