Observations and Outcomes in Experiments

Mr. Cahill guides seventh-graders through a lab activity involving four test tubes. Each test tube is filled with distilled water, and different amounts of sugar and yeast are added to observe reactions. Balloons are placed on top of the test tubes to capture any gas produced. Observations are made at intervals of 15 minutes, 1 hour, and 3 hours to note changes. The activity concludes with students recording their observations and analyzing the results.

What is the purpose of using distilled water in all test tubes initially?

• To make the solution acidic

• To increase the temperature of the solution

• To act as a solvent for sugar and yeast

• To change the color of the solution

Which test tube serves as the control in this experiment?

• Test tube number four

• Test tube number two

• Test tube number three

• Test tube number one

What is added to test tube number two?

• One gram of yeast

• Two grams of sugar

• One gram of sugar

• Two grams of yeast

What is the combination of substances added to test tube number four?

• Two grams of sugar and one gram of yeast

• Only yeast

• One gram of sugar and two grams of yeast

• Only sugar

Why are balloons placed on top of the test tubes?

• To prevent evaporation

• To add weight to the test tubes

• To measure gas production

• To keep the test tubes warm

What should students do after setting up the test tubes and balloons?

• Add more sugar to the test tubes

• Start heating the test tubes

• Remove the balloons

• Make initial observations and record them

After 15 minutes, what is observed in test tube number one?

• Gas production

• Color change

• No changes

• Significant changes

What should students do after one hour of observation?

• Remove the balloons

• Shake the test tubes again

• Add more yeast

• Record observations in the data table

What is the final step after three hours of observation?

• Finalize observations and analyze results

• Remove the test tubes

• Start a new experiment

• Add more sugar

What is the expected outcome for test tube number one throughout the experiment?

• It will change color

• It will produce gas

• It will remain unchanged

• It will overflow