Counting Trees


Counting Trees

Pupils devise a method for estimating the numbers of trees in a plantation then use their method to estimate the numbers of two different kinds of tree.

Practical details

National Curriculum levels 4 to 7
30 minutes to 1 hour
Ruler, pencil, calculator and paper

Key Processes involved

Simplify a complex situation and choose an appropriate method to use to count the trees.
Use a method of sampling to estimate the numbers in the plantation; use the relative proportions of the two kinds of trees.
Interpreting and evaluating
Consider the validity of the results.
Communicating and reflecting
Communicate the method and reasoning clearly.

Teacher guidance

Check that pupils fully understand the context, for example with questions such as:

  • Does anyone know what a tree plantation is?
  • How is it different from a natural forest?
  • Can you see which are the old trees, the new trees and the spaces in this plantation?

Pupils can tackle the task in different ways, but they might be expected to:

  • solve simple problems involving ratio and direct proportion
  • understand and use the formula for the area of a rectangle
  • choose a sample, collect discrete data and record them in a frequency table

The last slide in the presentation is to be used for a final plenary to facilitate discussion of sampling method.