Natwerk Designs

How would I evaluate this experimental design?

A student wanted to investigate the relationship between the amount of available light and growth of bean seedlings during a one week period. The student placed four identical seedlings in a sunny kitchen windowsill. She built a chickenwire frame around and over each seedling. On one frame she wrapped a layer of cheesecloth; on another she wrapped two layers of cheesecloth; on a third she wrapped three layers of cheesecloth and on the fourth four layers of cheesecloth. She measured the height of each seedling after a week to determine how much they had grown

Public Comments

1. Plants need full spectrum sunlight to grow. Being filtered by window glass, I would expect all the plants to be equally deprived of UV and therefore equally stunted in growth. It's a poorly designed experiment. Put the same setup outdoors and I would expect to see significant differences leading to a valid conclusion.