In this phase, the teacher explains the concept in accordance with students’ answers
that they acquired as consequences of their previous experiences. They identify acids and bases by using the
physical properties, the relation between acids and bases clarifies that the strength of acid solutions increases with
the amount of H+ ions while the strength of base solutions increases with the amount of OH- ions in the solutions.
The teacher gives examples for acidic and basic substances in daily life, explains that solutions with a pH value
lower than 7 is acid and a solution with a pH value higher than 7 is base, clarifies that a solution with a pH value
equal to 7 is neither an acid nor a base but a neutral solution. Then, the teacher states that strength of an acid
increases with a decrease in pH and strength of a base increases with an increase in pH, explains that NO2 and SO2
gases cause acid rains. Additionally, he/she presents scientifically correct explanation by using instructions based on
computers and examples from daily life in order to make concepts more clear.