Estimating environments

Activity

Use trees in the school grounds to improve estimation skills amongst Key Stage 2 or Second Level pupils. Look for other large numbers of natural items in the landscape to estimate.

  • Estimated time: 30 minutes
  • Location: Outdoors
  • School term: Early Autumn, Late Spring, Early Summer, Late Summer
  • Level of experience: No experience needed
  • Subject(s): Maths

Learning objectives

  • Use numbers in the context of the natural environment
  • Use knowledge of rounding to estimate the answer to a problem
  • Count forwards in multiples of 10

Preparation

Using dotty paper (isometric is better than cm2 squared), put a circle around 10 dots and look at the shape it makes. Now make 4 more nearby (without counting). This should total 50 dots. Look at the shape 50 makes and draw another 50 to make 100. Fill the paper with shapes of 100 and count the 100's. This makes a reasonable estimate, share the findings amongst the rest of the group or class.

Use this activity with pupils as part of a wider tree project or during National Tree Week which takes place in November each year.

Equipment

  • Electronic weighing scales
  • Isometric and cm2 squared paper
  • Pencils
  • Clipboards
  • A selection of 'fresh' leaves for weighing and measuring
 

Step by step

  1. Take your group outside and look for a specific tree, do you know what it is called? Ask the following questions; What is the total surface area of the leaves on a tree? How much might they weigh?
  2. Look at a small tree, estimate the number of leaves on each branch using the instructions from the preparation section. It may be easier to count in 20s or 50s. Try to imagine what a group of 1000 looks like?
  3. Next think about the surface area of the leaves. Draw around ten leaves on cm squared paper, count the whole squares and add every square that is more than half (but not any that are less then half). Total the ten leaves and divide the answer by ten. This is the average surface area of a leaf of that tree.
  4. Weigh ten or 100 leaves of the same tree, divide by ten or 100 to find the weight of one leaf.
  5. Display the findings in a visual way and remember to include the names of the trees.


 

Hints & tips

  • Can your group do the maths to find the photosynthetic surface area of the tree and the weight of it's leaves?
  • Could the group carry this amount of weight?