Classroom Update
 SIGNED progress reports DUE BY WED at latest – along
with any missing assignment.
 We will re-organize binders and share ANIMOTOS on Wed.
 Science In the News Current Event DUE BY APRIL 10th
 MUST have current article – within last 6 months
 MUST include article with WS
 Will be collecting DRY LAB on Thursday – Not HW; working
in class 2+ days
Using the Scientific Method
PHOTOSYNTHESIS "DRY LAB"
In this exercise you will be working
backwards.
In a normal lab situation you would be given a
procedure to follow and observations to
make.
In this lab, however, you will be given a set of
observations and asked to reconstruct the
procedures that could have generated these
data.
You will also be given a set of facts that you
will use to explain the observations. As you
work, remember the requirements for a
valid experiment. Review the Scientific
Method if you need to.
Good luck.
OBSERVATIONS
 Water plus bromothymol blue (BTB) is
blue-green.
 Water plus bromothymol blue plus an
aquarium snail turns yellow.
 Water plus bromothymol blue plus
elodea, an aquarium plant, is blue-green
in light.
 Water plus bromothymol blue plus a snail
plus elodea is blue-green in light and
yellow when left in the dark for three
hours.
FACTS
 Carbon dioxide in water produces carbonic acid.
 Bromothymol blue (BTB) is a blue-green liquid which
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


changes to a yellow color in acid and back to bluegreen when returned to a neutral pH.
Carbon dioxide plus water yields sugar and oxygen when
chlorophyll and sun-light are, present.
Animals respire.
Green plants photosynthesize in the light and respire all
the time.
Sugar plus oxygen yields carbon dioxide plus water and
energy
TASKS
Complete the following tasks on a separate sheet of paper:
 Write out lab procedures, which could have generated
these data. You may assume that you have access to as
many test tubes, snails, elodea plants, light sources, and
dark places and as much pond water and BTB as you
need or want.
 Explain each of the 4 observations given with a
separate statement.
 Write down three questions you have concerning
anything you think might be missing or incomplete about
the information in this worksheet.
Scientific Method Review
6th
 Hypothesis – an educated prediction about outcome of
test or experiment
Scientific Method Review
7th
 Problem or Question – found by observations
 Research – background information; all variables
 Hypothesis – an educated PREDICTION; has to be
testable
 Experiment –
 Materials – needed to carry out experiment
 Procedures – Steps to follow to test hypothesis
 Data – observations – qualitative (adjectives);
quantitative (#’s)
 Analyze Data – does it prove or disprove hypothesis
 Communicate results - share
Scientific Method Review
4th
 Question or Problem – based on observations
 Research – to gain background knowledge; what are
the variables
 Hypothesis – an educated PREDICTION;
 Materials – what is needed
 Procedures – what steps to follow
 Data – qualitative (adjectives) or quantitative (#’s)
 Conclusion – analyze data
 Communicate – share results
Scientific Method Review
2nd
 Question or Problem
 Research – background information
 Hypothesis – an educated PREDICTION; cause-effect;





testable
Materials
Procedures – controlled experiment
Collect Data – Qualitative (adjectives) or Quantitative
(#)
Conclusion - Analyze results
Communicate - Share results
Scientific Method Review
1st
 Question
 Research
 Hypothesis – An Educated PREDICTION; has to be testable
 Materials needed
 Procedures – steps to follow to TEST hypothesis
 Observations – Qualitative Data (adjectives);
Quantatative Data (numbers)
 Conclusion – how does data support/prove or not
support/disprove hypothesis
 Communicate – share results
Materials &Procedures:
 Snail
 Test tubes
 Elodea
 BTB
 Water
 Light & dark
spaces
 Test tube rack
1. Gather all materials
2. Set all test tubes in rack
3. Fill all TTs with __ mL of water and ___
mL BTB
4. Take 1 group of 10 TT and mark them
CONTROL
5. Take 2nd group of 10 TT and mark them
Experimental 1. Add 1 snail to each
6. Take 3rd group of 10 TT and mark them
EXP 2. Add 1 elodea to each
Materials &Procedures:
 Snails
 Elodea
 Test Tubes
 BTB
 Water
 Light source
 Test tube rack
1.
2.
3.
4.
5.
6.
Place # TT in TT rack
Fill each with ##mL water and ##mL of BTB
Leave 1 group of TT alone
In group 2 put 1 snail into each TT
In group 3 put 1 elodea into each TT
In group 4