Equipment Needed
Owing to its easy access most of the year the River Darent at Horton Kirby is ideal for a practical study supporting Unit 14 of the QCA Scheme of Work 'Investigating Rivers'.
Activities carried out depend on time available, weather and safety conditions of the river. However a typical visit would normally begin with a study by Westminster Bridge. If the water level is low and safe enough, children usually measure the width, depth at metre intervals and investigate the rate of flow using coloured sponge balls over a ten metre length.
Three pupils may each drop a red, green and blue ball positioned across the river beside the bridge, while nine children will be needed as catchers at the end of ten metres. There will be three pupils keeping time, each with a stopwatch.
The aim is to find out if some areas of the river flow faster than other parts and why.
Pupils are encouraged to carry out a fair test so that they realise why the balls should be dropped from the same height. Also each ball should be collected at the end of the same ten metres. Stopwatches are used to time the balls. Children may then find the width of the river and its depth at one metre intervals after estimating.
After leaving Westminster Bridge it is useful to stand in Westminster Fields and look back across the valley towards the viaduct. The flat area is a flood plain and used to be the river in prehistoric times. The area flooded during the winter of 2000/2001 for several weeks.
The group normally moves on to the meander where pupils may observe the effect of erosion and deposition and how the current has influenced the shape of the river. If time permits, pupils may carry out a field sketch of the area, though it is often more useful to take photos and draw from these back at school.
After visiting the meander the group usually walks to the river just north of Franks Bridge. It is normally shallow on the path side, gradually deepening across the river to the far side. Like the river at Westminster Bridge looking north it is straight but there is a bend towards Franks Bridge. This has allowed the current to flow faster on the outer bend, so causing erosion, while the slower inner bend has created a shingle bank where deposition has taken place.
Pupils who have been less involved earlier will carry out most of the measuring here. Once again nine children hold the red, green and blue balls in three different positions across the river with nine catchers placed downstream at ten metres. The balls will be timed as before and stopwatches used.
The results are often quite different from Westminster Bridge with the red ball furthest from the path (A) invariably travelling fastest, the green ball in the middle (B) less fast and the blue ball (C) passing quite slowly above the shingle and silt bank. There is often a definite pattern of results and much to discuss back at the Centre, or school.
In the afternoon pupils usually view slides of parts of the river which they visited on their mornings walk. Aerial photos, together with areas not seen earlier such as the source near Westerham and its mouth north of Dartford are also shown. This visual material provides a chance for pupils to discuss, reflect and reinforce their thoughts on the mornings findings. There are opportunities to look at maps and identify where a number of still photographs were taken around Horton Kirby and its environs.
Curriculum Relevance
A River Study may enrich pupils' knowledge, skills and understanding of places, patterns and processes.
Supports the Key Stage 2 theme 'water and its effects on landscapes and people' and Unit 14 'Investigating Rivers', QCA Schemes of Work