Intended Learning Outcomes
* numbers will vary from one / student to one / every four students
** best to have at least one / two students. Overhead transparency markers (non-permanent) work well.
Time Frame and Sequence
This material is designed to be used multiple times throughout the unit. In a 9-week unit, data will ideally be gathered three times approximately once every 3 weeks. In addition to gathering data, students will assemble 3-dimensional domes on which to gather the data. They will also spend time analyzing the meaning of the data they have collected.
Day 1: Set up & Student Predictions (Week 1)
Setting up the material for data gathering will take about 1/2 of a class period. This involves having students make a prediction by drawing the apparent path they think the Sun will take for the day on the inside of the plastic dome. It is preferable for each student to have an individual dome on which to predict, but if practical concerns do not allow for this, small group predictions can also work.
Students will then answer a few prediction questions on the lab activity sheet that accompanies this data collection. Examples of such prediction questions include: What direction did you predict on the dome for todays Sunset? How many hours of daylight do you predict there will be today?Lastly, students will assemble the dome on which to collect apparent Sun path data. This construction involves noting directions on the Hemisphere Base Diagram and then attaching it to a piece of cardboard of almost the same size. The plastic dome is then attached (taped or stapled) to the cardboard, on top of the diagram. You will need to obtain your own cardboard pieces to use with this activity (see photo). Domes and compass crosshair diagrams are available through Project STAR (www.starlab.com/psgi.html).
Day 2: Data Collection (Week 1)
The domes must be placed outside in a sunny, dry, and undisturbed location for an entire day (while Sun is in the sky). Tennis courts have proven to be a fine location. Check with colleagues (especially those in the department of physical education) before deciding on a site. Orientation of the domes is important and thus, especially for the first data gathering day, you may want to use a compass to ensure that the directions on the domes are aligned directly with the actual compass directions. This means that on a data gathering day, the domes should be placed in their designated location as early in the day as possible and not moved until data collection for the day is complete. Therefore, you may want to set them up and take the first data point yourself before school starts, or assign this task to a student who arrives at school early. Consequently, you should not plan to gather data with these domes on the same day that students assemble them.
It is ideal to gather as many data points as possible. Collecting one data point each hour is a good plan. Actual data gathering takes as long as you need to walk to the domes, mark a point and walk back to your classroom (approximately 10-20 minutes). The first time students gather data will take the longest as they will not be familiar with how to mark the domes. It is best if you demonstrate this procedure outside on one of the domes rather than trying to describe it in the classroom. A clear description of this technique is included in the lab activity. Once students have plotted their points, you may want to ask them to note the time above or below the dot as well. Encourage them to write both legibly and small if you have them record this optional information. Remember, during all these steps of data collection, the domes should never move. Remind students to bend down to the domes when marking them, rather than picking them up and making marks.
To gather data each hour, many possibilities exist. If there are multiple classes, each class can plot a different data point on the same set of domes. If only one class exists, then getting students to commit to devoting a small amount of their study hall or free period time to gathering data for the whole class is an option to consider. After the final data point for the day has been gathered, the domes can be moved and brought into the classroom. NOTE: it is not necessary for the domes to be in the same location on different days for ease of planning, it is desirable to use the same location on each data gathering day.
Day 3: Data Interpretation (Week 1)
As soon after the first data gathering day as possible, students should look at the data on their domes. They tend to be curious about what the domes will look like once an entire days worth of data has been collected. If you have class time available, this can allow you to build on their enthusiasm about the data. You can plan for this data interpretation to take about 1/2 the class period.
First, have students make a smooth curve through the data points to represent the apparent path of the Sun on the day the data was gathered. Students tend to have difficulty connecting the data points for a given day along a smooth curve. This is especially apparent when it comes to connecting the horizon (base of dome) to the first and last data points for the day. The curve tends to meet the horizon abruptly rather than continuing in the smooth curve angle already established. Use washable transparency markers to allow students to redo these as needed. The final curves rarely smudge with these markers. Have students write the date on which the data was gathered above or below this smooth curve again, have them write small and legibly.
Giving students an opportunity to examine their dome with this data is now a good idea. You may want to have them get together in small groups and see if they can determine what information this dome now holds regarding the Suns apparent path across the sky. Students will likely need a little time just to look at the dome with this new data on it before they see any real information in it. Things you can expect them to notice include the direction of the Sunrise and Sunset, how high the Sun was in the sky (especially its maximum height), and how many hours of daylight there were. They will also tend to make comparisons between the data and their predictions. At this time in the activity you may want to ask them what they predict the data will look like in three weeks or whenever you plan to take the domes outside to gather data again.
Having a discussion at this level of data interpretation is reasonable at this point in the material. You may want to have similar discussions after each of the next two data collection days. Students will then have more data and can discuss more about patterns they are beginning to see. More discussion will happen later in conjunction with material 2F: Seasons, regarding why and how the Sun's path appears as it does.
Days 4-5: Data Gathering (Week 4)
Again, set up domes and collect data for one day. Allow time on Day 5 for students to draw and date the smooth curve on the dome representing the day's Sun path.
Days 6-7: Data Gathering & Interpretation (Week 7)
On Day 6, have students collect a final days data. On Day 7, have students draw and date their third smooth curve. They will also need to complete the discussion questions on their lab activity sheet. Examples of these discussion questions include: From what direction did the Sun actually rise according to the dome data? Discuss how the points and smooth curve you drew for your prediction compare with the points and lines plotted using actual data.
Now that the students have a dome with three data curves, a discussion concerning patterns in that data would be appropriate. Building on the initial discussion involving this data (Day 3: Data Interpretation), this pattern discussion should focus on similar topics sunrise and sunset directions, angular height of the Sun and length of day and how these changed over time. Relating these patterns to the predictions that the students made would also be a logical focus of this discussion.
Collecting data and identifying patterns in the data are two of the three major steps in the learning structure within this EMS unit. The third step, building a model to account for these Sun position and day length patterns, occurs primarily in conjunction with material 2F: Seasons.
Student Ideas and Teaching Strategies
Students will probably be unfamiliar with gathering data in this way. It is worthwhile to have a discussion with them before the activity about how they think they might be able to gather data about the position of the Sun in the sky. They might offer a number of different strategies, after which you can describe the use of a 3-dimensional dome for data collection. Exposing students to this new method of data gathering is a very positive aspect of this activity.
It is important to let students know why they are gathering data but not using it right away. In general, they tend not to have experience in science gathering data over a relatively long period of time before they use it. This data will be applied when seasonal issues are addressed and incorporated into the EMS model (see Material 2F: Seasons).
It is fun to take these domes outside in as many different seasons as possible. Gathering data in the name of science in the depths of winter can be pretty exciting! Thus, even though gathering data for this activity could feasibly end after 3 collection dates, you may want to continue your collection until you see the data pattern reverse (after December 21 or June 21). Gathering data once every month is a reasonable time frame if you choose to extend your data collection. The students EMS model should help them understand this data and even predict it.
Students will probably predict that the Sun will rise directly in the east, set directly in the west, and pass directly overhead no matter what day you ask them to make this prediction. The domes have ridges on them and this seems to influence student predictions. It is important that the prediction data goes on the inside of the dome so that it remains for comparison later. Most students think their predictions are right and while gathering the first days data, they may think they are doing something wrong because their points do not fall on the predicted curve. They are often tempted to erase their prediction once they see that it does not match the actual data. Placing it on the inside of the dome to start prevents this temptation from becoming a reality.
Students may not realize that the dome can also provide data about day length. Asking students about how the domes can be used to gather such information usually leads to someone noticing this possibility. Basically, to gather day length data using these domes, students need to notice that there are 24 nubs around the base of the dome. Then, looking at one days data, count how many of the nubs are underneath the smooth curve representing the apparent path of the Sun. In this way, they can determine for what portion of a 24 hour day the Sun is visible in the sky.