science teacher's guide - DepEd Naga City

Teacher's GuideModule 3: Elements & CompoundsTeaching Tips• Run down the procedure before doing the activity. Together,visualize what is supposed to be done. Have one complete setup thestudents can look at while emphasizing some procedures. Ask somequestions as you go through each step, for example:• Procedure 1: What are the components of a 5% sodiumhydroxide solution? (Sodium hydroxide and water.) How muchin percentage is each of these components present in the saidsolution? (95% water and 5% sodium hydroxide.) What is thecomponent that is of highest amount in the solution? (water.)• Procedure 2: What is the basic solution referred to? (5% sodiumhydroxide solution) Why is it referred as a basic solution?(Sodium hydroxide is a base.)• Procedure 4: Here is the dry cell, where will you connect the redwire? (Positive terminal.) How about the black wire? (Negativeterminal.)• Assess your students’ capability in doing the activity. If you findthat the students are not yet ready to be the ones to do this, youare free to make this as a demonstration activity instead.• Emphasize the difference in behavior of the the two products. In thepresence of a flame or spark, hydrogen gives off a “pop” sound whileoxygen induces a brighter spark. You may also try doing the samething with water. Collect some water vapor in a test tube and inserta glowing stick/flame. Nothing is supposed to happen. This will letthe students observe that these three exhibit different behaviors,hence are different substances.Answers to Activity QuestionsQ1. A “pop” sound was heard.Q2. A brighter spark was observed.Grade 7 Science: MatterDiversity of Materials in the Environment 30