Subject: Natural Science Duration: 40 minutes Grade: 4 Primary/Elementary

General Aim: Development of Skills /Acquisition of Information

Specific Aims: To lead children through observation and experimentation, to formulate the concept that light travels in a straight line.

Basic Method: Reasoning

Preparation: Teacher: Has viewed film "Light for Beginners".Cards with holes, candles, curved and straight tubes, torch and slide projector are in readiness. Board illustrations have been prepared.

Reference:

CONTENT	PROCEDURE
Step 1:     Why is it necessary to invert slides so that we may view their projection correctly?	Setting the Problem On pretext of aiding the teacher, children are led to discover the need to insert slides upside down in a projector. Teacher poses problem.
Step 2: Expt 1: 3 Cards with holes through centres are arranged so that an observer can see an object. One card is moved out of alignment. What happens? Expt 2: The shape of a light beam's edge from a masked flashlight is examined. Expt 3: Subjects attempt to view a hidden object using straight and curved tubes.	Observation of Data Several simple demonstrations are performed involving as many children as possible. Onlookers are asked to record procedures and results. The importance of replication of experiments and accurate recording of procedures and data is stressed.
Step 3:   Anticipated findings: e.g. Rule: Objects are seen when presented in a straight line or path to the eye. Light travels in straight lines.	Formulation of Rule (Generalisation) Through teacher questioning findings are recalled and collated using board illustrations.           Children are encouraged to define the principle which governs viewing in each case. Questioning is employed to clarify and extend student observations where necessary.
Step 4:	Application of the Rule Children attempt an explanation of the inversion question raised in Step 1. Note: Attention is drawn to the importance of specifying conditions for the event to occur e.g. the projector lens is an important factor. Children are commended for contributions to the experiments and to discussion. Children commence recording of findings.