IB Internal
Assessment
(Lab) Scoring
DESIGN- Aspect 1
Defining the problem and selecting variables
Complete/2
Partial/1
Not at all/0
Formulates a focused problem/research
question and identifies the relevant
variables.
Formulates a problem/research question
that is incomplete OR identifies only some
relevant variables.
Does not identify a problem/research
question AND does not identify any relevant
variables
Examples of scoring: Formulates a focused problem/research
question and identifies the relevant variables.
• Background Info: Catalase is an enzyme found in
nearly all organisms exposed to oxygen. In our cells
it is located in peroxisomes & converts harmful
hydrogen peroxide into water & oxygen. 1
QUESTION: What is the effect of altering
the pH on the function of catalase?
– Is this question focused? (Do you know exactly what the
experimenter wants to find out?)
• Do you know what levels of pH are going to be tested?
• Do you know how the “function” of the enzyme will be
determined?
1
http://en.wikipedia.org/wiki/Catalase
Examples of scoring: Formulates a focused problem/research
question and identifies the relevant variables.
• Background Info: same as previous slide
• QUESTION 2: What is the effect on the rate of
oxygen production when hydrogen peroxide and
catalase are in a pH environment of 3, 4, 5, 6, 7,
and 8?
– Is this question focused? (Do you know exactly what
the experimenter wants to find out?)
• Do you know what levels of pH are going to be tested?
• Do you know how the “function” of the enzyme will be
determined?
Examples of scoring: Formulates a focused problem/research
question and identifies the relevant variables.
• Background Info: The movement of water from areas of
high water availability to areas of lower water
availability is an important process in all living things. 1
Without it, water would not enter roots cells from the
soil nor would water be able to enter the cells of out
body. 2
• QUESTION: How do different concentrations affect
osmosis?
– Is this question focused? (Do you know exactly what the
experimenter wants to find out?)
• Do you know what is going to be tested?
• Do you know how the movement of water will be determined?
1 http://arbl.cvmbs.colostate.edu/hbooks/cmb/cells/pmemb/osmosis.html
2 -jdldjodgopdgdopd
Examples of scoring: Formulates a focused problem/research
question and identifies the relevant variables.
• Background Info: The movement of water from
areas of high water availability to areas of lower
water availability is an important process in all
living things. 1 Without it, water would not enter
roots cells from the soil nor would water be able
to enter the cells of out body. 2
• What would you need to know in order to
write a focused research question?
• Your turn! Use this info. to write one.
1 http://arbl.cvmbs.colostate.edu/hbooks/cmb/cells/pmemb/osmosis.html
2 -jdldjodgopdgdopd
What are variables?
• any factor, trait, or condition that can exist in
differing amounts or types
• An experiment has three kinds of variables:
– Independent (IDV)  what is different in order to
test the hypothesis/answer the question
– Dependent (DV)  the data that is collected
• What data are you collecting as you stand at the lab
bench?
– Controlled  these are all the other things that
could be different but you want to keep constant
• This ensures that the data you collect allows you to
answer the question with confidence
Aspect 1 variables: IDV & DV
• QUESTION 2: What is the effect on the rate of
oxygen production when hydrogen peroxide
and catalase are in a pH environment of 3, 4,
5, 6, 7, and 8?
– Independent (IDV):
• Levels of pH (3, 4, 5, 6, 7, 8)
– Dependent (DV):
• Correct DV example: oxygen levels
– at time 0 sec, 30 sec, 60 sec, 90 sec, etc. (this is 4 pieces of
data)
• Incorrect DV example: rate of oxygen production
– (you had to do math to get this #)
DESIGN- Aspect 2
Controlling the Variables
Complete/2
Designs a method for the effective
control of the variables.
Partial/1
Designs a method that makes some
attempt to control the variables.
Not at all/0
Designs a method that does not
control the variables.
Controlled variables: Aspect 2
• QUESTION 2: What is the effect on the rate of oxygen
production when hydrogen peroxide and catalase are
in a pH environment of 3, 4, 5, 6, 7, and 8?
– Controlled variables: What things can you think of that
must be kept constant? Brainstorm with a partner!
•
•
•
•
•
Temperature of H2O2 & catalase
Volume/amount of H2O2 & catalase
Source of H2O2 & catalase
Time intervals oxygen readings are taken
Equipment taking the reading
– What are things that are not really important to list here?
•
•
•
•
All IDV levels tested in the same room
Same level of humidity outside
Same amount of light
Same person pouring H2O2 & catalase together
Controlled variables are displayed in a chart & they
are included in the procedure.
Controlled Variables Chart:
Controlled Variables
(state the variable; no
magic #; list what is needed
Temperature of enzyme &
substrate
Y
Z
How Method Allows for the Control of these
Variables
(explain how not “why”)
Both the hydrogen peroxide & catalase were
kept at room temperature (23ºC)
Note the use of the metric system!
Practice scoring: IB Sample #2
*Before we look at the controls, let’s score Asp1 while we read.
QUESTION (this person embedded their question information in a hypothesis)
Aspect 2: Controlling the variables
• What controls do you see in this procedure?
• Same person tasting leaf
• Same scale used to rate the leaf bitterness
• Mouth cleansing procedure for after eating a leaf (crack & water)
• What else could/should have been controlled?
• Amount of leaf material tasted/tested
• Part of the leaf tasted/tested
Practice scoring: IB Sample #3
(Asp 1 first, then Asp 2)
QUESTION (this person embedded their question information in a hypothesis)
Aspect 2: Controlling the variables  Example #3
(pass out procedure handout)
• What controls do you see in this procedure?
• Test tubes left in water bath for 30 minutes
• All apple cube sizes are 1cm3
• Same pH
• Same amount of substrate (2 cubes of apple)
• Volume of enzyme (pectinase) in each tube
• What else is controlled but isn’t listed in the chart?
• Total volume in each test tube
• Same type of apple
• Method of crushing the apple to extract juice
DESIGN- Aspect 3
Developing a method for collection of data
Complete/2
Develops a method that allows for the
collection of sufficient relevant data.
Partial/1
Develops a method that allows for the
collection of insufficient relevant
data.
Not at all/0
Develops a method that does not allow
for any relevant data to be collected.
“Method,” “Sufficient,” “Relevant”:
• Develops a Method: Procedure is complete & explains all
necessary steps
• Sufficient:
– at least 5 different levels of IDV
– at least 3 trials at each level of IDV (5 is better)
• Relevant:
– data collected will actually allow you to answer the
question
• Ex: If you are trying to measure the amount of bacteria that
is on your desk as the day progresses & it is used, you must
sanitize the desk before you begin the experiment.
Aspect 3: Develops a method… tannin in leaves experiment (Ex #2)
• All steps included that allow another person to complete the experiment?
• No; How were the leaves chosen?
• Sufficient Data?
• No; only 3 levels of IDV
• Not really quantitative; more qualitative (better if he quantified the amount of light)
• Relevant Data
• Yes; Student is equating bitter tannin taste to level of light & he is tasting for
bitterness.
Aspect 3: Develops a method… pectinase & pectin
(Ex #3)
• All steps included that allow another person to complete the
experiment?
• No; Students Introduction mentioned a rate of reaction for pectinase
& the experiment didn’t discuss how to measure the rate of the
reaction.
• Sufficient Data?
• No; only 1 trial completed for each level of IDV (need at least 3; 5 is
better)
• Reality of how much juice 2 small apple cubes will yield  small;
apparatus says to use 25mL beaker & this would be too big
• Relevant Data
• Yes