Please read the following before starting an exercise:
The topics of this exercise are "system concept, gravity force, sound media waves, weathering and erosion, change of physical properties, analyze and interpret evidence, construct graphs for evaluation, explain atoms/elements/molecules/compounds".
If you need to study the topics, please do so before your exercise.
The exercise will take about 10 minutes. Our system starts to count time, when the exercise is loaded. Make sure you are not interrupted.
Select "Start Exercise" when you are ready. After you submit your answers, Beestar will grade your exercise.