Cyanobacteria are algae that live in body of water, and can manufacture their own food. In certain conditions these algae can proliferate fast. This is called Cyanobacteria bloom, and it can become toxic and damage the ecological balance of the body of water. There are several accepted chemical and biological treatments to reduce the bloom. One of these treatments is the addition of special dye to the body of water, which blocks the light transmission through the water.
Watch the following video demonstrating the effect of dye addition to water on their light transmission:
During February 2016, Cyanobacteria bloom was observed in Lake Kinnert.
In your question you describe
an interesting phenomenon which is hardly known in Israel. It was nice to learn
However the question is relatively
simple and challenges only few aspects of the student's skills. The background
contains description of several facts. The student needs only to deduce a logical
deduction, once he is familiar with the term photosynthesis.
The student gains new
knowledge. He/she should understand the dye treatment to reduce the bloom
of the Cyanobacteria. However, a simple logical analysis of the last sentence: "One
of these treatments is the addition of special dye to the body of water, which
blocks the light transmission through the water", is enough to
understand that it is a different phasing of the correct answer.
All the other possible
answers were not so misleading or distracting. It was relatively simple to understand
that they are incorrect.
It was assumed that the student is familiar
with the term Photosynthesis, which is reasonable assumption for the defined Piza
In addition, the map-point
"Reduction of cyanobacteria in domestic aquarium",
which is very good and educated, contains the answer: "Reduction of
light for 3-7 days. This step reduces the photosynthesis process, thus the
cyanobacteria cannot produce nutrients crucial for growing and may starves".
The background presented
prior to the question as literal text, in addition to the student self-knowledge
about the term photosynthesis were sufficient for answering the question correctly.
The video is nice but does not add new information. The Kinerret photo is a nice
addition but doesn't contribute additional data that should assist the learner
when answering the question, or maybe I didn't manage to see this data.
There is no need for
higher levels of data processing, such as graph or table analysis, experiencing
simulation or observations from watching video or animation.
1.You can add a graph
or a table that shows the relationship between the percentage of the reduction
in the Cyanobacteria bloom and the amount of dye per a fixed area. This should emphasis
the effect of the amount of the light on the reduction process. Using this table
or graph you can also add to your question and answer a relation to the minimal
amount of light blocking that is required to stop the algae bloom.
2.You can add a
video of how cyanobacteria community is being controlled in an aquarium by light
3.The question is
dealing with reduction of the algae proliferation. However it is not explained in
the background in which conditions these algae can proliferate faster. I
think this data should be added such that the question directing to
photosynthesis is still challenging.
4.If the Kinerret
photo contains algae view then they should be marked with some circles or arrows
and additional text.
I think there is
nothing new that I can add after the things that Aya has said .
really like the topic , its very interesting and new for me , after I read the
question I have done a lot of researches on the internet to read more and to
know more in order to add a point on the map and to give a right evaluation for
your question , and I really enjoyed that .
a lot of researches and looking deeply into the topic , I think that this is an
easy question at least for me , it doesn't require thinking and its doesn't
take time to know the right answer .so I think you should make it a little bit
the video and the picture that you added on the body of the question itself , I
think they are bonus and there is no need for them , I didn't get the point of
the picture , and the video although its look like its authentic ,it didn't add
any new information for the question , its just formatted the formula of the
question in other way that the student can see what are you talking about
information that you inserted on the map's points , are very useful and
interesting and new and related to the main topic of the question , although it doesn't really help the student
to solve the question , its just an addition to the knowledge he has acquired
of reading the text of the question.
me I really don't understand the connection between the points on the map
(places) and the information that you wrote on it .
suggest putting 2 pictures of the same lake one with the Cyanobacteria bloom and the other one is after we
treated the bloom and restricted the proliferating of Cyanobacteria for compares .
also suggesting replacing the video with another one that explain how the Cyanobacteria proliferating and why , and how the
dye restrict the proliferation .
I think you should explain the term photosynthesis aside
,because I think not all the students of junior school know this term and what
it does and how it works . In addition , I think you made the question very
easy for the student , that there is no need to look on the map's points and
read more , so he can solve it by just reading the body of the question , so I
think you should put less information on the body of the question and make him
look and search on the map's points and read to solve the question .
In general , I really liked this topic
, and it was really fun and enjoyable to read about it , and I think you really
did a great job .
I like the subject that you chose to write a question about,
and the video that you added, it shows the relevance of adding dye that
influence the light transmission through the water.
You said that there is bloom of the cyanobacteria but you
did not mentioned when it is happening and in which circumstances and
conditions; like mentioning the lake stratification and that the bloom happens
at the summer as a result of the lake stratification.
Also I felt that there was short of the definition of the
cyanobacteria, you did not mentioned the properties of this kind of algae, for
instance that this kind is characterized in atmospherically nitrogen fixation, you
can use this information by this attached link to understand more about this
You mentioned that there are another treatments to reduce
this bloom but you did not mentioned just this treatment with dye, I was
interested to hear more about the treatments so I can evaluate why you chose to
talk about this specific treatment.
Honestly I did not like this treatment because in my own vision
I see that this treatment could damage another organisms, that also use the
photosynthesis to survive, and the organisms that Nourished of the damaged organisms,
I think that this treatment would bring several symptoms to this lake.
will now refer to the updated question as follows:
are algae that live in body of waterwater bodies, and can
manufacture their own food. InThere
are certain conditions in which
these algae can
proliferate fast. This is called Cyanobacteria bloom, and
ita condition that
can become toxic and damage the ecological balance of the body
of waterwater body.
There are several accepted chemical and biological treatments to
bloom. One of these treatments is the addition of a
special dye to the body of water, which blocks the water’s
light transmission through the water.
have a look also at the possible answer and consider updating.
question, after the introductory paragraph and associated video and
image, was “How can the blockage of the water light transmission,
using a dye, help reduce the Cyanobacteria bloom in lake Kinnert?”.
if I assume correctly, the right answer is the one including
a word that never came up, neither in the introductory paragraph nor
the video or the image.
Question's name is: "Chemical
reduction of Cyanobacteria bloom", I find the term "chemical
reduction" here rather ambiguous, as it is a well defined
chemical term, which you here give a different than normal meaning
content is rather relevant and might be good to associate with
climate change if relevant (it seems it is relevant)
people before me said, the possible answer alternatives, are for from