Teachers TryScience

Part 1: Scale of Examination

1. In lesson 1, students learned about models. Direct students to the Understanding portion of the THINK app. Have a student read aloud the brief description on the Understanding landing screen.
2. Instruct students to spend a few minutes exploring the various models that have helped humans to answer a variety of questions such as, “Will the plane fly?” and “How does disease spread?” As they are exploring, they should make note of the scale on which these questions were examined. An individual level? A city level? A country level? Something else?
3. After about 5 minutes, ask a few students to share their observations about scale. They will notice that problems occur at different scales and so innovations must happen at different scales as well.
4. Tell students that currently, there are climate adaptation activities taking place primarily on the city level. Ask why students think this might be the case. (Climate change impacts are often felt at a local level. For example, sea level rise impacts New York City differently than areas in other parts of New York State. Additionally, cities are equipped to respond in a more targeted and expedient manner than federal governments.)
5. Rather than a city level, tell students that they will investigate potential climate change impacts on a school level. Again, these impacts will be related to precipitation, and again, they will use models to understand interactions between systems.

Part 2: Intense Precipitation and Drainage

1. Increased precipitation might mean more incidences of flooding or more severe flooding. Many cities and towns have aging drainage systems that were not designed to respond to higher levels of precipitation. Tell students they will investigate how drainage systems might respond when a severe rainstorm strikes.
2. Split students into groups of 3-4. Tell students that they will be examining different features of the water system within a town. Inform students that during an average rainstorm, this hypothetical town receives 500 mL of water over a 3-minute period. Their challenge is to create a model of the town that can withstand this type of rainstorm.

3. Tell students that first they will sketch a neighborhood. The neighborhood can look anyway they like, but their sketch must at least indicate the following features:

Street drains

Rivers, lakes, or streams

Wastewater treatment facilities

Any hills or valleys

A school building, a house and a hospital

Roads leading up to the school building

4. After students have had time to sketch, it is time to build. Using the materials you have provided to them, have students use their sketch to create a physical model within the trays provided. Below is an example of how students may use the materials. You can provide this as a key, or allow them to decide for themselves.

Street drains- empty funnel

Rivers, lakes, or streams- soil with water

Wastewater treatment facilities- funnel with food coloring and water that has been stopped up with clay

Hills or valleys- soil

Buildings- clay

Roads- cardboard

5. Once building is complete, it is time to test. Have one student in each group serve as a timer and another serve as the “rain.” The “rain” should be sure to slowly pour the water onto the model neighborhood so that the process lasts for the full 3 minutes. Other students should record what happens to the different features of the model.
6. Have students share their observations.
7. Tell students that they will now repeat their test with the same amount of rain, but with a shorter amount of time. Instruct students to remove as much of the water from their model as they can.
8. Now, have the “rain” pour 500 mL of water onto the model in 1 minute.
9. Ask students how this more intense rainstorm affected their town. Were roads affected? Were drains able to take in all of the water? Did the wastewater facilities run over? How might this effect the school?
10. In this case we are talking about intense rain. Ask students how the scenario might change if there were extreme snow?
11. Again, tell students that it is not accurate to attribute a single storm to climate change, but storms will be become more frequent and intense in some parts of the world, so it is important to understand the impacts they may have on our lives.

Part 3: Drought and Evaporative Cooling

1. Now that students have examined potential effects of heavy rain, ask students what effects drought may have on their area.
2. Split students into groups of 3-4. Tell them they will be building a sling psychrometer. Tell students that a psychrometer is used to measure the water content of air, and that this can be used to find relative humidity. Ask students what relative humidity means.

PSYCHROMETER

3. Ask a representative from each group to get the materials for the experiment.
4. Instruct students to place both thermometers along the side of an empty plastic bottle. The thermometers should be situated so that only the tops of the thermometers are touching the bottom of the bottle, and most of the thermometers are allowed to hang freely. Students should secure the thermometers to the bottle using a rubber band or tape. Students will be swinging the bottles, so the thermometers should fit securely
5. Students can tie a string to the neck of the soda bottle. The string should be long enough to allow students to swing the bottle freely, but not long enough to hit anyone.
6. Finally, have students tie a piece of wet stocking to one of the thermometers. The thermometer with the wet stocking will be known as the “wet bulb”. The other is the “dry bulb” .
7. Once all groups have finished building tell students that they will be swinging their psychrometers for one minute and then immediately reading first the wet bulb and then the dry bulb thermometer and recording the temperature. They should swing the psychrometer like a pendulum, and not over their head or in a circle. Stress that it is important to be aware of others when swinging the psychrometer, and that the point of swinging the tool is to get air flowing across the bulbs. Students can either swing using the string, or by holding the top of the bottle, but they should be sure not to touch the thermometers.
8. Allow one student per group to swing for one minute. Another student will serve as the timer while the other group members record results.
9. Have each group put the temperature readings from both the wet bulb and the dry bulb on the board so everyone can see the results. Using the data they’ve collected, ask students to explain why there was a difference in temperature. (The evaporation process cools the wet bulb thermometer, resulting in a lower reading.)
10. Each group should then use the class data in conjunction with the Relative Humidity Worksheet to find the average relative humidity and answer the associated questions.
11. After students have had time to complete the worksheet, review the questions as a class. Be sure students understand that evaporation is a cooling process. You can use the Evaporation video in the Resources section to illustrate this idea. Students will have also observed this concept when measuring the difference between the wet bulb and the dry bulb, but when humidity is high, evaporation is slower because the air is already moisture laden and has less of a capacity to absorb additional moisture. This is why in humid conditions the difference between the two bulbs would be smaller. Less evaporation can take place in humid conditions, so the wet bulb does not cool as much as compared to the dry bulb.
12. Now have students sketch a diagram that represents the transfer of energy that took place during the evaporation process. Help students understand that energy that otherwise would have heated an area goes to the evaporation process resulting in a cooling effect.
13. Tell students that up until now, they’ve been talking about what happens when the atmosphere has a lower capacity for absorbing moisture. Ask students to now consider how this concept of evaporative cooling might relate to situations where there is less water available for absorption, such as in the case of a drought. Tell students that in abnormally dry areas, there is less water available for evaporative cooling. This means that in addition to being dry, these areas may be hotter.
14. Ask students how less evaporative cooling might affect the school? (Hotter temperatures will increase the amount of energy needed to cool buildings in order to keep them at a safe temperature. School buildings with outdated air conditioning units, buildings that aren’t shaded, and buildings made of materials that heat up quickly could feel the absence of water’s evaporative cooling effects.)

Part 4: Drought, Soil, and Building Foundations

1. In addition to less evaporative cooling, a decrease in water may affect the school building in other ways. Split students into groups of 3-4.
2. Tell students that they’ll investigate how soil responds in the absence of moisture, and the effect this has on the foundation of buildings.
3. Have students lay the soil out in the tray or bin. Using the soil, they should devise a way to make the cardboard stand as straight as possible. If necessary, they can add a bit of water to the soil. This represents part of a building’s foundation.
4. Students should then place the heat lamp over their tray. They should work with their groups to develop a hypothesis about what impact the heat lamp will have on the soil and the cardboard.
5. After about 7 minutes, students should record observations about the soil and the placement of the cardboard. They should notice that as the soil begins to dry out, it begins to contract, leaving a gap between the soil and the cardboard. In some cases, the cardboard might fall over a bit.
6. Then, add 10-15mL of water back into the soil around the cardboard. What happens? (The soil expands, pushing against the cardboard.)
7. Ask students what they think would happen to a building’s foundation or school’s sidewalk if it continually faced periods of soil contraction and expansion? (It would start to crack or shift.)
8. Remind students that drought and flooding are just two potential climate change related impacts. Similarly, stormwater runoff, decreased evaporative cooling, and building damage from soil contraction and expansion are just a subset of how precipitation impacts will affect human systems.