Trigger questions
What do plants need to survive? (water, soil, sunlight)
Most plants drink water from the ground through their roots. The water travels up the
stem of the plant into the leaves and flowers, where it makes food. (This process is
called photosynthesis - process by which C20 and H20 in the presence of light are
converted to sugar and oxygen). Plants do this by soaking up sunlight in their leaves
and using the nutrition from the soil.
What happens if you cut the roots of a flower?
When a flower is cut, it no longer has its roots, but the stem of the flower still drinks
up the water and provides it to the leaves and flowers.
What happens if plants drink something other than water (e.g chemicals, insecticides)
It may affect the plants health and growth.
What happens if you put a flower in a cup of coloured water?
Before the children conduct their experiment – ask them to write down their
hypothesis (ask the children to guess the answer).
Using food colouring does not harm the plants in any way but allows children to see the
journey the water takes from the roots to the shoots.
In time the food colouring will be sucked up the stem along tiny tubes (called vessels)
and the petals of the flower will start to change in colour.
‘Flower Power‛ Activity
Materials you will need:
ü Water
ü Red food colouring (you can use green and blue too if you wish)!
ü Jam Jar
ü White flowers (one per group) e.g Carnation, Chrysanthemum, Marigold
Steps:
1. Fill the glass jar with 2cm of water.
2. Add 25 drops of food colouring.
3. Put the flower in the water (ensure that the flower is either freshly cut or trim
the stem of the flower at an angle to create a fresh cut).
4. If possible, ask the children to check the flowers every few hours to record any
progress. It may take up to 24 hours for the food colouring and water to
journey from the stem to the petals (but the results are worth waiting for!)
Conclusion
Trigger: What has happened? (Hint, look very closely at the petals and the stamen (the
bits in the middle of the flower). Ask the children to record their findings on their
worksheet
Experiment conclusion and discussion
Let‛s find out what happened to the flowers in each group. Ask each group to announce
what happened to their flower, and how long it took for the colour change to occur.
Why do you think the flower changed colour?
The flower absorbed the water through the stem and because the water was coloured,
the water turned the petals this colour. Did you know that plants need water to live?
Like humans, plants are living things which need food and water to survive. Nutrients
from the soil and water are absorbed through the roots and stems of plants.
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