Controlled experiments see Year 5 Science students ascertain the optimum conditions for plant growth.
As Year 5 students continue with their Science topic on habitats, they’ve begun to take a closer look at the conditions that best suit the growth and survival of plants. A class discussion before the half-term break led them to compile a definitive list of the key things that are necessary to sustain plant life: light, warmth, water, mineral nutrients and carbon dioxide.
To investigate whether a living organism can endure without one or indeed some of these, Dr Ryalls instigated a controlled experiment with the girls. It involved them placing 10 cress seeds into six different petri dishes. The first dish they placed on a warm, well-lit windowsill. The next they put in a dark place. They left the other four without warmth, water, fertiliser and carbon dioxide respectively.
Now they are back at school, the class took another look at their specimens this week to measure the length of the plants that had grown. They were able to see cress tips responding to warmth, moisture, nutrients and light and sprouting in the ‘control’ dish.
The seeds left in the dark had grown long and spindly tips in their quest to seek out light. In a similar vein, the seeds without fertiliser had grown to a certain extent, buoyed by the nutrients carried within them, but had then died once their food source was exhausted. The dishes lacking warmth and water, however, had failed to propagate at all.
The girls noted and recorded any changes from which they were ably placed to draw scientific conclusions.