# KS2 Maths - Measurement

### Learning Objective: Angles

Estimation - Pupils continue to measure using the appropriate tools and units, progressing to using a wider range of measures

### Resources

String

Tape measure

Ruler

Square shaped paper..

### Introduction

Take the children to a local woodland, or simply find a big tree in the school grounds. Ask the children how big they think the tree is and ask the children how they could measure the tree. There are a few options to estimating and measuring the tree, the paper method and the shadow method and talk through the methods with the children then put the children in to two groups.

### Paper Method

Use this method to find the height of a tree without doing any maths. All you need for this method is a piece of paper and a tape measure.

• One child should fold a piece of square shaped paper in half so that it forms a triangle.

• Fold one corner over so it forms a triangle with the opposite side, then cut off the extra paper above the triangle. They should be left with the triangle they need.

• Ask the child to hold the triangle in front of one eye by holding a corner opposite from the 90 degrees right angle (see the above picture), and point the rest of the triangle toward them.

• One of the short sides should be horizontal, the other vertical.

• Ask the child to move back from the tree until you can sight the top of the tree at the top tip of the triangle.

• They should close one eye and use the other to look directly along the longest side of the triangle, until they see the exact top of the tree. They want to find the point where their line of sight follows the longest side of the triangle to the very top of the tree.

• The triangle will have one right (90 degree) angle and two 45 degree angles.

• Mark this spot and measure the distance from it to the base of the tree. This distance is almost the full height of the tree. Add your own height to this, since you were looking at the tree from the height of your eyes off the ground. Now you have the full answer!

• One child should stand with their back against the tree trunk, with the second child facing their partner, but they need to move back a few steps.

• Child 2 closes one eye and holds a pencil between thumb and first finger, vertically at arm’s length, so that the point is level with the top of the tree, and their thumb is level with the base of the tree.

• Child 2 stays in the same place and turns their hand until the pencil is horizontal, keeping their thumb level with the base of the tree.

• Child 1 walks away from the tree to the side so that they appear to be walking along their partner’s pencil.

• When they reach the end of the pencil, Child 1 should stop .

• Now, using a tape measure, Child 2 or another member of the group measures the distance between Child 1 and the tree. This measurement is approximately the same as the height of the tree.

### Extension

Repeat this method with a number of trees in the area, and compare the estimations with the measurements