Your students have just entered grade 8. If students have largely mastered the concepts taught till grade 7 as per NCERT, which of the following will they most likely NOT be able to describe?

Option 3 : The role of current in inducing chemical changes. 

Concepts of the curriculum are arranged in a pre-defined order where the students go from simple to complex. The depth of the concept increases as they get promoted from one grade to the other. If the flow of concepts is not taught in the pre-defined order then the students have to face problems in understanding some concepts. The students of grade 7 are likely to master the following topics in the concept of heat and electricity:

• Symbols of electric components.
• The wires used in making electric fuses and the uses of electric fuses.
• The functioning of an electric bell. 
• The role of insulators in thermo flasks. 
• The effect of current on a compass needle. 

​On the other hand, the role of current in inducing chemical changes will not have been mastered by the students as the topic is above the cognitive level of students it will be introduced in the later stages of their learning.

Hence the role of current in inducing chemical changes will not be mastered by the students who have just entered grade 8.​