The Needs of the Plants

The child explores basic Botanical facts, through the following experiments.  The Needs of Plants opens up this Botany work with three experiments

  1. The Needs of Seeds/Plants (small group presentation to a group of four children)

Material Description:

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Four shallow dishes, cotton wool, some quick sprouting seeds (cress/mustard), watering can with a rose attachment, paper, pencil and scissors, tissue, small spoon

Method:

Begin saying, “We are going to find out something about the needs of seeds to grow healthily”.  Does anybody know what these seeds will eventually become? …   We are going to do some experiments”

Make a base of cotton wool in each of the four trays and sprinkle half a teaspoon of seeds on each tray, get the children involved.

“What sorts of things do you think these plants will need?”.  When they identify the need for water pour water into three of the four plants.  Ask a child to write a ticket ‘No Water’ and to place it in front of the appropriate saucer, or write the ticket and involve the children in the spelling.  When they suggest heat write a ticket for ‘no heat’ and put it by some watered seeds, do the same for light(in a cupboard) and heat (fridge with a torch).

Say about the final dish “This one will get light, heat and water.”  Ask the children where they think the dishes should be placed, beginning with the one that gets everything.  Remember to water the ones without light and heat and the one with no water with the one with everything.

The children are responsible for watering the plants and observing what happens to the seeds, on a sheet of paper in their own way over the next few days. When the experiment is finished inspect the cress or mustard and let the children eat them.

When to give these lessons:

In the very early days, because the experiments take a while to complete, after the Story of God Who Hans no Hands and the Time-Line of Life, the experiments can be done in parallel.  Through their observations children will have made a synthesis of the needs of plants and then can go into the Work of the Leaf.

2. The Need of the Plants for Light

Material Description:

Black box with opening at both ends, quick sprouting seeds (cress/mustard) a seed tray, cotton wool or compost, watering can

Method:

Begin saying, “We are going to find out something about what happens if seeds don’t have light”

Make a base of cotton wool on the seed tray and sprinkle the seeds generously, get the children involved, sprinkle compost (if you are using it), then water them.Place the tray into the black box

Water the seeds over the next few days and wait for them to become established, when they are four or five centimetres tall, open the box at one side and place it in the direction of a well lit area.  The children will observe that the plants begin to bend towards the light (phototropism).

Then, leaving the box where it is close the box and open the other side.  The children will observe that the plant bends towards the light.  They might want to repeat it a few times.

Discuss with the children, “Which parts of the plant are looking for the light?” (leaves and stems)

Notes- to correctly direct the light:

  • The box must be tall enough for the light to reach the plants
  • The seed tray should be fit the floor of the box
  • Cut the windows so that they are in line with the top of the tray and not too wide
  • It should be black so that light isn’t reflected.
  • The flaps should close as tightly as possible.

3. The Need of the Plants for minerals

Material Description:

Six wide jars with wide necks and card or paper tops with holes in the centre (made by an X).

Six small plants with a root system and a few leaves, e.g. pea plants, all the same size at the same stage of growth grown in a soil free medium

Black construction paper may be used labels.

One litre of distilled water (mineral free) with one with 1 gram of calcium nitrate, potassium phosphate, 0.5 gram magnesium sulphate, few drops of iron or chloride in solution,

Jar 1 everything

Jar 2  distilled water

Jar 3 everything but calcium nitrate

Jar 4 everything but potassium phosphate

Jar 5 everything but magnesium sulphate

Jar 6 everything but iron or chloride

Method:

Present to a small group saying, “We are going to find out something about what happens if seeds don’t have minerals”

Fill the six jars with the solutions and label each ‘e.g. No Calcium Nitrate’, older children could number each jar and have a key.

Sit the root system of each plant through the hole in the paper, (optional – cover the jars with construction paper to limit the growth of algae which will react and keep the roots in the jar).

Wait and observe, topping up the solution with the prepared solution or distilled water.  Ask the children to record changes to the plants and measure them occasionally, over several weeks

Jar 1 everything – best growth

Jar 2  distilled water – no noticeable impact

Jar 3 everything but calcium nitrate – stunted growth

Jar 4 everything but potassium phosphate – stunted growth

Jar 5 everything but magnesium sulphate – stunted growth

Jar 6 everything but iron or chloride – yellow leaves

Conclude with the children, “Plant need minerals and water to grow healthily” (Show Chart A – Needs of the Plant) See what questions and comments arise, Ask them, “Can you see two parts in this plant, the part above the ground and the part below it. What do you notice about the part below the ground, we see routes and minerals in the soil. What do you think is happening?  How do these minerals and water get into the plant? What about the part above the ground? What does our chart show? It shows leaves and it looks as though carbon dioxide is all around the leaves.”  

Notes:

  • Good soil contains all of these minerals
  • We can see the chemical symbol for carbon dioxide, two parts carbon and one part oxygen.
  • Carbon Dioxide is shown here impressionistically, leave the chart up while the children are interested

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