science teacher's guide - DepEd Naga City

Teacher's GuideModule 1: Solutionsd. Stir the sugar in each cup for 10 seconds and observe. Whathappened to the sugar?e. Record your observations.f. Stir for another 10 seconds and observe again.g. Set aside both containers.h. After 5 minutes, observe closely the bottom of the container.Salt in cold and hot waterRepeat Steps 1 to 7 with salt.7. Discuss the results of the investigation. Ask the following questions:• Does temperature affect how fast sugar dissolves in water? Give theevidence based on your observations.• Does temperature affect how fast salt that dissolves in water? Givethe evidence based on your observations.• Which dissolves easier in hot water: sugar or salt?Expected results:For sugar: Sugar dissolves faster in hot water than in cold water. Twoteaspoons of sugar can completely dissolve at room temperature inthree minutes. But, two teaspoons of sugar can completely dissolve at75 o C in one minute and 13 seconds.For salt: There is about the same amount of salt remaining at thebottom of both the hot and cold containers. Only a little more salt candissolve in very hot water than in cold.Students can conclude that temperature affects how fast sugardissolves in water more than it affects how fast salt dissolves in water.This conclusion is based on the difference in the time needed todissolve sugar in cold and in hot water. However, there is only a slightdifference in the time needed to completely dissolve the salt in hot waterthan in cold water.8. Let students use their observations to make statements about the effectof temperature on how fast salt dissolves in water as well as how fastsugar dissolves in water.9. When all groups have completed their investigation, compare theresults.Grade 7 Science: MatterDiversity of Materials in the Environment 12