Pass the Globe Activity

Purpose: To help students personalize their understanding of the Earth's position in space and its relationship to the seasons and dates of the year.

 

Materials:  1 to 12 globes, lamp, and 4 to 12 desks or tables.

 

Experiment

    Set up:  One or more standard globes (12" diameter - although any size will work as long as they are all the same). Students are to be seated in a circle, preferably at desks or tables (single seats can be used.  The globe must be positioned to be at the same level off the floor for the entire activity.  The circle works best if its divided into twelve portions).  A single light bulb lamp (without the lamp shade) is set at the center of the circle (a little pre-set up: position the light bulb so the light shines on the globe). Be sure the light bulb is at the same height as the equator.  Make one entire wall "north" (if you know which way is really north use the real direction).

            The student's positions are to be labeled with dates.  Depending on the age of the students, they can make place cards with the dates - the dates can be their birthdays (or the teacher can make the date cards ahead of time).  You should/could have (at least) the first and 15^th of each month.  The desks are labeled with the dates as follows: due north=December 21^st; due west=March 21^st; due east=September 21^st; due south=June 21^st (90 degrees from each of these- with 12 desks, each desk could be a month).  Figure out the in-between dates as portions of the 90 degrees (ie: 45 days from December 21^st is February 5 - halfway between north and west).  The room needs to be as darkened as possible - the darker the better.

 

Procedure: The activity is best done with multiple globes - however, it can be done with a single globe.  Students need to be told to keep the globe with the north pole facing the north wall for the entire activity - emphasize that as the Earth travels around the sun, it keeps the exact orientation of its tilt in exactly the same direction. 

After everything is set up, before the activity is begun, students could be asked what they think the set up is a model for.  Eventually, they should guess - or perhaps be told - that this is a model of the Earth's path (orbit) around the sun. 

Certain questions should be asked and discussed such as (based on the age of the students): how long does this take? (365 days). What is this called? (one year). What does the Earth do as its going around its path? (it rotates on its axis). What is this called? (one day).  How is the day divided?  (into hours).  What are the lines on the globe?  (Latitude,  longitude). Etc.

The idea of the activity is to position the Earth at any date, rotate the Earth, and see how much of the Earth is lit up during the daytime, and darkened during the night time particularly at different latitudes.  By personally "passing the globe" from one student to another, students get to see what the globe looks like at the date at which they are sitting (which may be their birthday).  Students should change seats and check out the globe from different vantage points.

 

Concept: The amount of day light changes day to day, based on the latitude and the Earth's position around the sun.  Differences between day and night are observed when the Earth is rotated.  We can note how the seasons are "off" when compared to the traditional dates due to our northern location.

 

Tips:  Seasons are arranged counterclockwise. December would be North (winter solstice). March would be West (Spring Equinox). June would be South (Summer Solstice). September would be East (Autumnal Equinox).

This activity works best if globes are stationary and students move.

 

 

Extension Activity

     If your students are having difficulty understanding the concept that direct light produces more heat than indirect light, you may wish to do the following experiment.

 

Purpose:  To demonstrate that direct sunlight produces more heat than indirect sunlight.

 

Materials:  light source, thermometer, and black paper.

 

Experiment

     Construct an envelope out of the black paper that will hold the thermometer. The black paper should cover the bulb and the lower third of the thermometer. Set up the light source so it is parallel with the thermometer. Record the temperature after 30 minutes. Change the angle of the thermometer to a 45 degree angle.  Record the temperature after 30 minutes.  Change the angle of the thermometer to a 90 degree angle. Record the temperature after 30 minutes.  Compare the temperature readings and draw conclusions from the data.

 

Concept:  Direct light produces more heat than indirect light.

 

Tips:  Question students about the relationship between the two experiments.  The amount of time may need to be adjusted to show a change in temperature depending on the intensity of the light source.