Lesson 1.2:
Enquiry
7th
Grade
Introducing …
People use arguments in everyday life to change
someone’s thinking or opinion about a topic. For
example, I could argue that KFC sandwiches are
better than Subway sandwiches because I want our
family to buy from KFC restaurant this week. To
convince my family that KFC sandwiches are better, I
could provide my reasoning:
● KFC pairs better with cheese.
● I like the taste better.
● The colors of the KFC, lettuce, and tomato look
more appealing together.
The reasons that I believe KFC sandwiches are better
are NOT scientific because they are NOT based on
data. The reasons I stated are just my opinions. In the
field of science, arguments use evidence and data
rather than belief or opinion to support a claim
because evidence and data can be reexamined and
retested, whereas beliefs and opinions cannot be
verified.
What does a tree use to build
its trunk and leaves ?
Question
One possible explanation :
Evidence
Tree take their food from soil ?
Jean Baptista van Helmont tested
this idea (400 Y ago)
Experiment:
Van Helmont weighed a pot of dry soil
and willow tree seedling. Then he
planted the seedling and watered it for
5 years. The willow gained 73kg and
the soil only lost a few grams.
After 5 years
Experiment
New explanation:
If the tree took all its food from soil; the soil
should lose as many Kgs as the tree gains.
This didn’t happen, so there must be a different
explanation
Plant cannot grow
without water
Plants are made from
water
Malpighi’s evidence
Marcello Malpighi (1670) ask new questions by
looking at leaves on ,microscope:
● Do leaves make the food that plants use for
growth?
● Do the leaves send this food down to their roots ?
Experiment:
He cut the leaves off a
seedling. The seedling
still had a plenty of water.
Results:
Seedling with removed
leaves stops growing.
Hales’s evidence
Experiment:
Stephen Hales
(1727) grew a
plant above
water, inside a
jar.
Results:
The water level
rose. Some of the
air had gone.
Plants take something out of the air
Changing explanations:
Scientists build on each others’ work. Over
time, other scientists have shown that:
 Leaves use a gas from the air, as well as
water, to make food.
 Leaves needs light and small amounts of
minerals absorbed from soil throught
their roots.
Homework : Page 11
Lesson 1.3:
REVIEW
7th
Grade