This is what I had for initial thoughts. Any ideas. Struggling to find inspiration in KS3 syllabus. How common policy makers can make science sooo boring?
Transpiration.
The tackling of this topic assumes pre-knowledge of leaf structure ? if this abscent then can be filled at review level.
Introduction:
Ask for volunteer.
Ask class to image volunteer is stood in the sun without the benefit of deordorant. What would happen -try to illicidate individual would sweat.
Now imagine that volunteer is not a person but a plant would they still sweat?
Yes ? by process called transpiration.
Review leaf structure
Summarise pictorially the leaf structure and stomata
When plants sweat ? transpire they loose water through evaporation from the stomata
Water movement
Summarise the passage of water through a plant.
When water is lost through the evaporation from the stomata it creates a gap in the leaf which allows more water to be drawn up into the leaf. This continues through the plant until the gap has reached the roots and more water is drawn into the roots from the soil. This water entering the roots is cool and brings with it important nutrients. Thus nourishing and cooling the plant.
Factors affecting transpiration.
Find original volunteer or new volunteer if original uncomfortable
Imagine volunteer is stood outside all year, what would happen to them?
Thought activity to think about:
Temp, light, Rain/water availability level, wind. Etc
Take key factors and ask
if hotter would volunteer sweat more, colder
if raining would the amount they sweated change
Wind?
Light?
Relate to plant.
Possible flash application illustration
Transpiration Adaptations.
Plants in hot climates have adapted to loose less water through transpiration. This is achieved by changes to the surface area of the leaf and reduce numbers of stomata.
Summary.
Transpiration is the evaporation of water from the stomata of the leaf
Transpiration creates a temporary small shortage of water in the leaf which draws water up through the plant and roots.
This help to transport minerals into the plant from the soil
Transpiration is greatest when the plant is in hot, windy, sunny and dry conditions and least when the plant is in damp, cold, dark and windless conditions
Plants in hot climates have fewer stomata and less transpiration to help preserver their water.
ADDITIONAL:
Depending on time availability and specific syllabus emphasis there is the scope for the inclusion of an experiment session using potometers to test the impact of the various factors and if possible the lesson plan would have to be adapted such that the individuals could drawn their own concl