Rain Gauge

Description:
The rain gauge measures the amount of liquid precipitation that falls.  It can measure either rain or, with added steps, the liquid equivalent of snow.  The rain gauge has an outer cylinder, a measuring tube, and a funnel.  The measuring tube measures to a hundredth inch.  When it is full, it contains one inch of rain.  When more than an inch falls, the extra flows into the outer cylinder.  By carefully pouring the rain from the outer cylinder back into the measuring tube, a total rainfall amount can be accurately measured.
When snow is to be measured, bring the entire gauge into a warm room.  Allow the snow to melt.  Then follow the same procedures as above.

Goal:
Students will be able to measure rainfall to the nearest hundredth (.01) inch, understanding that rainfall is part of the water cycle and a necessity for life on earth.

Instructions for Set Up
The bracket of the gauge should be fastened to an upright post that allows the gauge to sit above the ground.  The top of the gauge should be 5 inches above the top of the post.  The gauge should sit firmly in the bracket.  Placement should be away from any buildings, trees, walls or other tall objects that would distort the readings.

Rain Gauge
Activity:  Rain Is Falling All Around

Objective:  Students will be able to measure the amount of rain in one rainfall event to the nearest hundredth (.01) inch.

Materials:  Rain Gauge

Time:  45 minutes before a rain event is predicted and 45 minutes  after the end of a rain event where the gauge has been used to collect the entire rainfall.  There should also be time taken before the beginning of the rain event to observe the changes in the weather.

Background Information:
The rain gauge measures the amount of rain (or snow as liquid) that falls to the earth as part of the water cycle.  This is called precipitation.  Too much or too little rain can cause problems for living things on earth.  Scientists record the amount of rainfall both in a single rain event and over time to compare it to other times and other years.

Procedure:
Introduce the students to the rain gauge before a rain event is predicted. Show them the easily read gradations of .01 inches and how they would add each hundredth to the tenth.  For example, three small lines above .40 would equal .43 or 43 hundredths. Using a chalk or white board, have students figure out a number of possible readings or use the rain gauge worksheet. This may also be used as an extension activity. Discuss the reasons we might want to know how much rain falls (i.e. gardening, sports events, reservoirs and wells). Provide information on how to use the rain gauge to measure rain and best placement for the instrument.  Show the students where the gauge will be placed at the school.  Have them check to make sure it meets the criteria for proper placement.
Assign the task of listening to or watching the weather forecast.  Ask the students to report when a rain event is predicted.
Alert the students to the possibility of rain. Before the beginning of the rain event, have students pay attention to the general weather changes.  If the have studied clouds, their understanding of cloud types could be utilized at this time.  The same is true for the study of the barometer.  If not, a general observation of changes could be made.
After the rain event, bring in the gauge.  Have students observe it.  Did rain flow into the larger cylinder?  Have them predict how much rain fell.  Measure the actual rainfall to the hundredth-inch. Have the students estimate the length of time the rain lasted.  After going over the work sheet for the single event rainfall, have students fill out the sheet individually.
Have them return as a whole group to review their work and understanding.

Rain Gauge
Activity:  Collecting Snowfall Amounts

Objective:  Students will be able to use the rain gauge to measure snowfall as liquid precipitation. They will be able to express a relationship between the amount of snowfall and liquid.

Materials:  Rain Gauge  with measuring tube and funnel removed

Time:  45 minutes

Background Information:
The students will have been introduced to the rain gauge and understand how to read it to one hundredth of an inch.  If the rain gauge has not been used before, the lesson "Rain is Falling All Around" should be covered or modeled with water in the classroom.  The students will understand that snow is precipitation and part of the water cycle. Snow, when melted, is measured like rainwater.

Procedure:
When a snow event is expected, make sure the cylinder is placed appropriately so that snow may be collected. Have children verify that the location of the cylinder meets the criteria for placement.  It may have to be collected several times to get an accurate precipitation reading.  If the goal is to help children understand the amount of snow that makes up one inch of water, the cylinder need only have some accumulation of snow in it.
Meet as a whole group. Bring in the cylinder with a significant amount of snow in it. Let it melt at room temperature. Have the children predict how many inches of water they will have when the snow has melted and ask several to explain their predictions. Write their predictions on a chalk or white board with their initials beside them. Discuss the relationship of temperature to snow and how that relates to various climates.  Ask the students how snow might change their plans for a day and how else it might relate to living things.
When the snow in the cylinder has melted, slowly fill the measuring tube as many times as needed to measure the amount of fluid precipitation.  Write the total precipitation on the board.  Have the children find the prediction that is closest.  Was it a guess?  Did the student have a reason for his/her prediction?  What do the children think now about the relationship between snow and rain amounts?  How does this explain the larger amounts of snowfall in the winter and the lesser amounts of rainfall in the summer?  The discussion may be closed by a listing of factual statements the students can now make about snowfall amounts in terms of precipitation and climate conditions.

The Rain Is Falling
Single Rain Event Recording Sheet

Name  ________________

What did you observe about the weather before the rain began?

How long did the rain event last?  ___________________

Did the rain overflow the measuring tube?   ___________

What does this mean?  ___________________________

How many times did the rain from the cylinder FILL the measuring tube to the top?   _______  That equals the number of whole inches.  There were ______ inches of rain from the rain event.

Was there rain left over that did not fill the tube?   ______  How much rain was there in hundredths of an inch?  _______

How much rain fell all together?   __________

This curiculum project was funded by the Colby Partnership for Science Education, the Howard Hughes Medical Institute, and the Bell AtlanticFoundation.