The boiling point project lesson can be divided nicely into a seven day unit allowing for 40 minute periods. The following is a suggested guide for each day's activities that is appropriate for middle school students but which can be adapted on a higher or lower level.
Through collaboration and experimentation, students will discover and understand the correlation between the boiling point of water and the elevation at which water is boiled.
Lesson Objective: Students will explore how the boiling point of water is determined.
The lesson will begin with the question: How do we know when water is boiling? Students' ideas will be written on board.
Students will divide into groups and boil a pot of water following the guidelines given in the experiment instructions . Students should record the water temperature at 30 second intervals and continue until the water is boiling at a constant temperature for at least 5 minutes.
Using a graphing program, have students graph time (x-axis) vs. temperature (y-axis). Once they've graphed this information, print out the graph and have students indicate on the graph the point at which boiling started.
Homework: Students should take home a copy of the graph and jot in their journal observations about why water temperature leveled off, how that leveling corresponded to the physical differences in the water and why there might be a relationship.
Lesson Objectives: Students will discover how boiling point is determined. Students will develop a hypothesis for the experiment and prepare a Letter of Introduction from their school.
Give students 10 minutes to discuss their journal entries from the night before. Write on board observations by students. If necessary, have the class send an email question to an expert (check the Online Experts page to find an expert) to find out why the water temperature leveled off and how it correlates to the boiling point. (As you heat a pot of water, heat first goes to raising the temperature of the water. At certain temperature, water has received enough heat to become a gas. That's the boiling point. After this point, heat won't go to increasing the temperature, but instead to converting the liquid to gas. Converting liquid to a gas takes energy, so you use energy from the heating device for this conversion.)
Ask the students whether they think that the temperature will level off at the same temperature today. At the same temperature tomorrow? At the same temperature at their homes? At the same temperature in Mexico? At the same temperature with different types of heating devices?
Tell the students that they will be participating in a collaborative project with students in other parts of the world to determine what affects the boiling point of water. Explain that all schools will be boiling water and determining their boiling point.
Have students come up with a hypothesis for the experiment. Ask them which factor in the experiment (volume of water, room temperature, school elevation, or heating device) will have the most effect on boiling point and why. In other words, which factor is responsible for determining the boiling point of water?
Have students prepare a Letter of Introduction from your school with information about the school, students, number of people in class, elevation of school, latitude and longitude of school (so students can pinpoint on map). Elevation, latitude and longitude information may be found using the links on the Reference Material page.
Lesson Objective: Students will determine the boiling point of water.
Divide students into groups to perform the boiling point experiment. Graph temperature vs. time again. Write down the date of the experiment, volume of water used, air temperature in room, elevation of room, type of heating device used and boiling point. Please refer to the experiment instructions . Note: Please have all students in the same class use the same volume of water and same heating device.
Lesson Objective: Students will determine the boiling point of water. Students will ascertain the location of project partners on map.
Begin by reading some Letters of Introduction from other participating schools (if available). Have students pinpoint other participating schools on a map.
Perform the experiment again in small groups. Graph temperature vs. time again. Write down the date of the experiment, volume of water used, air temperature in room, elevation of room, type of heating device used and boiling point. Note: Please have students use the same volume of water and same heating device as used previously.
Lesson Objective: Students will determine the boiling point of water. Students will find average boiling point and room temperature for the class. Students will submit data to the project database.
Perform the experiment for the third time. Graph the third set of data. Write down the date of the experiment, volume of water used, air temperature in room, elevation of room, type of heating device used and boiling point. Note: Please have students use the same volume of water and same heating device as used previously.
Have each group report their average boiling point for all 3 days of activity. Find the average boiling point based on results from the entire class. Also determine the average room temperature for all 3 days.
Submit your results to the project database. Please submit only one set of data per class.
Lesson Objective: Students will look at all data to determine if there is a correlation between any of the factors -- temperature in room, volume of water, elevation of school, or type of heating device used -- and boiling point.
In groups, students will look at the all data submitted by other schools in the project's database. Students will graph boiling point vs. each of the other factors. Students will look for correlations. Students will determine which factor in the experiment had the greatest correlation to boiling point. Please refer to the Analysis Instructions for more details. Students will draft an explanation for what they found.
Homework: In journal, write why they think they might have found a correlation among certain factors.
Lesson Objective: Students will explore the relationship between boiling point and elevation.
Teacher will begin by soliciting journal reactions. The relationship between boiling point and elevation will be discovered. Students will give reasons why they think this might have occurred.
Teacher will then lead into discussion of this phenomenon. The lesson will end by the class submitting a final report with their final conclusions to the project's Discussion Area.
Hopefully your students will find that at a different elevation (where the air pressure is lower) that the boiling point is lower. This is due to the fact that the water gas bubbles have an easier time forming. The air pressure isn't quite as heavy on them, so they can withstand the pressure at a lower temperature, and, thus the boiling point is lower. (Refer to the Background Information for further explanation.)