When teaching a unit or even a one off lesson, it is essential that the teacher is competent and has a thorough content knowledge. In order to achieve this, research must be conducted and references gained to help promote first the teacher's understanding, before this can be transferred to students. Following is an example of such, when a Science unit of work on plants was to be taught, I prepared some notes for myself, highlighting key theories and ideas, whilst also looking into some common misconceptions in students that i may come across, and hopefully be more prepared to deal with.
What Plants Need to Live and Grow
In order to live and grow, plants require a number of things; light, water, air, soil and food, which they must obtain from their environment. There are two major processes which take place in plants which provide food and energy. They are photosynthesis and respiration.
This is the process by which plants are able to produce their own food. This chemical reaction that takes place in plants, uses carbon dioxide from the air, water from the soil and sunlight to produce sugars and oxygen. The chemical reaction takes place in the chloroplasts, cells of the plant which contain the green substance chlorophyll.
These sugars are used by the plant to make starch and cellulose, whilst are combined with minerals brought up in the water from the stem help make proteins, oils and other chemicals for the plant cells. The food made by the photosynthesis process helps the other cells in the plant respire, grow and repair themselves.
This is the process which provides energy to keep the plant cells alive and takes place in the structure called the mitochondria. The sugars produced through photosynthesis are combined with oxygen to produce carbon dioxide, water and energy for the plant.
Children’s Common Understandings and Alternative Conceptions
Many children come to school knowing some information about plants, but few have really worked with plants in a scientific way. Therefore it is important that student’s prior knowledge is gauged, to set up an understanding of your own classes’ range of knowledge and experiences related to plants.
One alternative conception of plants is that they obtain food from the soil through their roots. This is easily associated with humans ingesting their food. It may almost appear to be an inconceivable fact for children that plants’ food originates from atmospheric gases and water (Dawson &Venville, 2008, p.25).
A slight variation on this alternative conception is that soil is the plant’s food, and chlorophyll is the plant’s blood. Again related to children’s association of their human body understandings with plants (Osborne and Freybrrg, 1985, p.62).
Whilst children might know that plants need water to grow and survive, it is possible that they also think the water is taken in by the plant by its leaves.
It is also possible that while children might be familiar with the term photosynthesis, and be able to give it in response to how plants make their own food, they may have no understanding of what the process actually involves. It is therefore important that student’s gain some insight into how the process actually works.