1. Learning at the macro level
Central to laboratory work is the proper observation of phenomena
Content knowledge is crucial for the proper interpretation of observations
Observational stimuli in experiments

2. Learning chemistry in the lab
What are the teacher goals for laboratory work?
What are the students’ goals for the same laboratory work?
How the students construct chemical understanding in the lab?
How the instruments that students use in the lab influence what phenomena are perceived and learned?
Chemistry requires much practice as well as extensive reading.

3. The Lab paradigma Lab offers direct experience with natural phenomena.
‘Laboratory appears as a way of allowing students to learn with understanding and at the same time, engage in the process of constructing knowledge by doing science’
However the relationship between experiences in the lab and student learning is not so simplistic.
Observations are theory-dependent and therefore fallible and biased.

4. Objectives of lab work
Verification of chemical principles (cognitive domain)
Simultaneous training in technical skill (psychomotor domain)
Developing and sustaining motivation to persevere in constructing chemical understanding
Developing metacognitive skills (creative thinking, problem solving, modelling capability)

5. Lab experiences provide students to acquire technical skills in working with equipment.
Lab work represent a significantly different area of learning with respect to content acqusition.
Inquiry-oriented lab activities appear to be better than lecture/demonstration or verification.
Properly designed lab activities
Lab work provides opportunities for data manipulation through the use of computers (graphs, spreadsheets).
Lab work involves learning how to recognise, estimate, eliminate and analyse errors (data analysis and representation).

6. Laboratory Instructional Types
Expository (deductive)
Instructor-centred: the learner follows a well-established procedure.
Minimize resources (time, space, equipment, personnel).
Inquiry (inductive)
Student-centred: Inquiry-based activities have an undetermined outcome and require the learners to generate their own procedures.
Students have to deal with a scientific problem for the solution of which they must plan and carry out an experimental investigation.
Pro: Group learning activity.
Problem solving strategies.
Con: Resources consuming.

7. Discovery (inductive)
Problem-based (deductive)
Without calling for new procedures, students are required to try an experiment.
Group learning activity.

8. Inquiry laboratory (Tertiary level)
Activity
Abilities and Skills
Formulate the problem
Pose scientifically-oriented questions
Relate the investigation to previous work
Form hypotheses
State the purpose of the investigation
Design and conduct scientific investigation
Identify the pocedure
Treat data
Perform the experiment
Formulate and revise scientific explanation
Criticize procedure and results
Communicate results

9. Criticism
Lab is a complex environment. Real achievement by the students is not obvious.
Value of the lab experience might be not measurable in a quantitative sense.
The value of lab work lays more in the motivation factors, than in the cognitive domain.
Lab work is usually poorly conceived, confusing and usually unproductive with respect to the extensive investment of time and effort by staff and students.
Students may not connect the phenomena observed/measured in the lab with chemical concepts.

10. Instrument may become a black box that hinders students’ construction of knowledge.

11. Good practice
Consider carefully the science content of the proposed experiment
Pre/post laboratory oral discussion
Laboratory actvities should have limited, specific goals
Design rhe labs so that the procedural skills or instruments are clusterd in several labs
Allow the students to ask the ‘what-if’ questions (exploring the boundaries)
Design computer-aided lab activities

12. Distributed cognition & lab activity
Distributed cognition recognises that knowledge can be distributed over the environment and the individuals and the artefacts/tools which interact in that environment.

13. In a real lab…….
The teacher set fire to a quantity of sulfur in a porcelain crucible and asked the student to describe what he had observed:

14. Selected readings
Hodson, D. (1990). A critical look at practical work in school science. School
Science Review, 70 (256),
Hodson, D. (1992). Redefining and reorienting practical work in school science.
School Science Review, 73 (264),
Nakhleh, M. B. (1994). A review of microcomputer-based labs: How have they affected science learning? Journal of Computers in Mathematics and Science Teaching, 13,
Pickering, M. (1993), The teaching laboratory through history. Journal of
Chemical Education, 70,