Thursday, 19 December 2013

Manipulative skills

Manipulative skills in chemistry internal assessment

Manipulative skills are assessed summatively. This means that one overall mark will be given. The skills
assessed should cover most of the two-year course, and the mark given should reflect the student’s general
ability near the end of the course. This mark is not an average nor does it relate to a given investigation. It is
important therefore that the scheme of work sets the students a variety of tasks and that they carry out a
range of different techniques. The examples below are suggestions to aid assessment of manipulative skills
and are not considered to be a prescribed list.
Note: No supporting evidence is required for moderation of manipulative skills.
Aspect 1: Following instructions
The student:
reads/listens to instructions before asking for help
only starts the investigation after having read/listened to all the instructions
is able to follow a sequence of several written or verbal instructions with little
assistance.

Aspect 2: Carrying out techniques
Measuring volume
The student:
uses a suitable cylinder/pipette/burette size
does not overfill cylinder/pipette/burette
places his/her eyes at the height of the meniscus.

Measuring mass
The student:
handles the balance appropriately when transporting it
adjusts the balance to zero before starting
uses a suitable container for the substance to be measured.

Measuring temperature
The student:
leaves his/her thermometer in a safe place when it is not in use
refrains from touching the sides of the container with the thermometer when
measuring the temperature of a liquid
leaves the thermometer in the liquid when measuring the temperature of that liquid.

(Vacuum) filtering
The student:
folds/places the filter paper correctly
uses equipment/filter paper of adequate size
adds a reasonable amount of liquid to the funnel.

Making solutions
The student:
uses a funnel to add the solid to the volumetric flask
washes the container containing the solid several times and adds the water to the
volumetric flask
carefully adds water to the mark.

Titration
The student:
makes one trial before taking measurements
takes at least three measurements
takes care towards the end of the titration.

Assembling equipment
The student:
ensures that different parts are clamped safely together without forcing the glass
uses anti-bumping granules for boiling liquid
chooses the correct size/shape of flasks
places the thermometer at an adequate height
connects the cooling water adequately.

Collection of gas
The student:
takes care that the assembly is airtight
takes care that the equipment does not contain air before starting.

Setting up electrical circuits
The student:
connects up a circuit without help
connects the ammeter in series and the voltmeter in parallel
connects the positive side of the ammeter/voltmeter to the positive side of the power
supply
uses a suitable scale.

Aspect 3: Working safely
The student:
always wears safety clothing appropriate to the task, such as eye protection, lab
coats and gloves
pays proper attention to written or verbal safety instructions and hazard symbols
lights and uses the Bunsen burner safely
places flammable substances far away from flames
takes care, when heating, that the test tube does not point at other students
takes care that the test-tube holders are not in the flame
ensures that solutions are not heated to complete dryness
places hot equipment on heat mats
uses the fume cupboard for all poisonous volatile liquids
washes his/her hands after using toxic substances in the laboratory
takes care not to mix spatulas for different chemicals, or caps off different bottles
leaves glassware on solid surfaces and ensures that glassware cannot be knocked or
roll off the surface
reports when equipment has been broken
avoids wasting chemicals
cleans spilled chemicals or broken glassware immediately
washes and tidies up the equipment after use
disposes of chemicals in a suitable manner

shows awareness of the impact of chemicals on the environment.

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