Diagnostic Test
Based on the diagnostic or remediation test results, a student’s “deficiencies” are determined.
Therefore the test must help the teacher to discover the deficiencies and help remove the road
blocks.
An example of a two tier multiple choice question to understand student misconceptions:
1. Covalent compounds have low melting and boiling points.
(i)
True
(ii) False
Reason
A. They have strong covalent bonds
B. They have weak intermolecular force of attraction
C. They are very volatile because covalent bonds are weaker than ionic bonds
D. They cannot withstand strong heating
The right concept: Covalent bonds formed between atoms are very strong. When a covalent
compound is heated, the energy is used to break the weak intermolecular force (van de waals’
force) of attraction between the molecules. The strong covalent bonds are not broken.
Student’s wrong concept: Covalent compounds have low melting and boiling points because
covalent bonds are weaker than ionic bonds.
2. Which of the following is true regarding the difference between tetra chloromethane
(CCl4) and magnesium chloride?
I Tetra chloromethane consists of molecules, whereas magnesium chloride consists of
ions
II Tetra chloromethane does not conduct electricity, whereas solid magnesium chloride
conducts electricity
III Magnesium chloride has a high melting point, whereas tetra chloromethane has a low
melting point
IV Magnesium chloride is soluble in water whereas tetra chloromethane is soluble in
inorganic solvents.
A I & III only
B II & IV only
C I , III and IV only
D I ,II , III and IV

Right concept : Ionic compounds such as magnesium chloride do not conduct
electricity in the solid state. It can only conduct electricity in molten state or aqueous
solution.

Student misconception: Ionic compounds like magnesium chloride can conduct
electricity in any state.
3. Element X forms X2- ion. Which of the following is true about element X?
I X has two valence electrons
II X is in group 2
III Ion X2- has an octet (stable) electronic arrangement
IV X is a non-metal
A I and III only
B II and III only
C I and II only
D III and IV only

Right concept: Non- metals will generally accept electrons so that the ions formed
will achieve the stable electronic configuration
Closing the gap
Building sound back ground knowledge is crucial for a student’s success in the field of science.
Since “learning comes from deep thinking” and deep thinking broadens existing schema, it’s
very important that as teachers we provide avenues for our students to broaden their horizons.
We are living in the age of social & economic changes, advances in technology, environmental
issues ,pollution & global warming and we need a thinking generation. We must encourage
reading habits by providing the right articles, internet sites, books etc. regarding specific topics.
We need students to be well read about current issues and challenges facing the world.
Building back ground knowledge helps them come out of their cocoon and understand and
appreciate the complexities and mysteries of our world.
As teachers we must mold our students to become “natural explorers”. One way as the article
mentions is through providing “direct and indirect experiences” to our students .Field trips
,factory visits ,educational videos , visits to museums, farms, aquariums ,science labs are all
learning hubs. When our class was doing a unit on stable structures we went for an educational
visit to the Toronto Tower .We must therefore strive to give our students the right exposure.
Most importantly we must encourage our students to become independent learners.