Sunday, April 10, 2011

Weathering and Erosion for Second Graders

On Friday I will be going into the second grade trying to educate and interest the second graders in various types of erosion.  This topic is listed under Virginia Science Standards 2.7:

  • Model the effects of weathering and erosion on the land surface.
  • Land surfaces are subject to the agents of weathering and erosion. Land surfaces that are not covered with or protected by plants are more likely to be subject to the loss of soil by wind and water
  • Weathering is the breaking down of rocks by the earth's atmosphere
  • Erosion is the process by which the products of weathering are moved from one place to another.
Because the devopment of curricula from scratch is a time consuming process and I am trying to get activities into the schools quickly, I don't always develop my own curricula, but often rely on books and sources from the web.  One source that I often go to which has a rich source of hands-on activities as well as lecture materials is  This resource has been under development for a while as a consortium of universities and funded by NSF (The National Science Foundation).  Because I was so enthusiastic about this site, I volunteered to become a reviewer.  As new activities or units are submitted, I am sometimes contacted to review the unit to ensure its quality.   In any case, you can search for ideas under subject area, curricula units, lesson plans or hands-on activities.  Because I don't do any formal teaching with this program, I have only used the activities portion of the site.  I found a unit for grade level 3 called "Glaciers, Water and Wind, Oh My!".

I will take you through my process of how I prepare before going into the classroom with an exercise like this.  In this unit, there are five stations to be set up, however, one of the activities involves using boiling water, not something you can do with second graders.  Instead, as the writeup recommends, I might try it as a demonstration.  However, before I even use this activity, I will try all of the stations at home with my own kids.  There are five activities:

  • Chemical erosion in which rock samples are subjected to a weak acid such as lemon juice or vinegar
    • First, I have to locate some marble.  Usually I will go beg for things in a store, or go through things we have laying around our farm.  We do happen to have some marble tiles left over from a project.  Another option is to use chalk.
    • Other rock samples that don't react with acid are also needed such as granite, gravel, and brick
  • Water erosion (this could be very messy!)
    • Need a large container of dirt and poker chips and a watering can
    • Pour water over a mound of dirt with poker chips embedded in the dirt
  • Wind erosion
    • Use sand and a small fan to blow the sand
    • This seems like a good experiment for the kids to observe and an adult to manage
  • Glacier erosion
    • Using clay, sand and ice cubes
  • Temperature erosion
    • Uses boiling water, cold water, and ice to see what happens to glass marble that is subjected to hot temperature and then quenched
Now I will show you how things went with the testing.

  1. First, I tried the temperature erosion activity.  You are supposed to drop a marble in hot water, with the heat source on, leave the marble for five minutes, drop it into water and then into ice.  I did this twice and nothing happened.  I know that you are supposed to see cracking or splitting, but nothing!  I am going to try this exercise in reverse to see if anything happens.  I will publish the results.  My guess is that the "new" marbles that I have are made differently from the "old fashioned" marbles we are used to seeing.  Needless to say, I will not be using this exercise!
  2. Next, I used a marble tile to show chemical erosion using vinegar.  There was no bubbling when I dropped the vinegar onto the marble, as indicated in the write-up stating that there should be.  What does happen is less than dramatic.  If you leave the vinegar on the marble for a few minutes you get some spotting, but for a group of 2nd graders, this is pretty boring, undramatic stuff.  I am still thinking of using something like this exercise, but I may use chalk or pennies, but I still have to think about it.
  3. For the wind erosion, you are supposed to form a hill of sand in the middle of a tub and using a fan or hair dryer blow the sand around.  I did this, and it does blow the sand around, but you also end up with sand particles everywhere!  And, isn't that what we all expected?  I may skip this one also.  I can't really let the kids use a hair dryer by themselves, we would end up with sand absolutely everywhere.  I am thinking of seeing if it is possible to do this with straws instead, but I will let you know after my kids and I try it.  The drawback to letting the kids use straws is again having sand in other kids' eyes.
So far, things are not going so well.  I need 4 or 5  activities.  When I do the science activities at the school with a class size of 21 or so, I try and set up the room to have four experiments with a volunteer at each station.  This gives a ratio of one volunteer to 5 students, which works well to oversee the experiments and engage the kids on one-on-one conversation and interaction.  So, back to the web to see what else I can come up with.  There are lots of sites out there posting science activities.  The key is to try them and as you can see from my results above, not all work as advertised.  I found a site called science class, which publishes lots of activities for various subjects.  In going through the geology section, there were lots of experiments on weathering and erosion.  I went through all the activities and found a couple that I thought might work well. 

Wave erosion: This activity was not in my original list, but it has the advantages of being simple, using cheap materials that I have access to, and being a bit messy and easy enough for kids to do.  First, I piled up some sand in a tub.

Next, I added a little bit of water to the tub, then I moved the tub back and forth making waves.  I also had my kids do this exercise.  They loved it!  What is the result?  I am sure you know:  we get beach erosion. 

Because this is a quick and easy experiment, you need to get a bit more of measurement in here.  First, as the science class web site recommends, have some rulers on hand to measure the height and width of the "beach" and draw a sketch of the beach.  Next, have the kids make five waves.  Now measure the results, have them do it again five times, and measure again, and finally, five more waves and measure one more time.  Have a data sheet ready for them to record the results.  Here is what ours looked like after 15 or so waves:

Yeah!! This experiment is a keeper and will engage thie kids.  Lucky for us, we have outdoor space for these experiments.  I will just have to haul in some extra sand, after five classes with four groups each making waves, we could get some pretty mush sand!

Next, I tried another exercise called mechanical weathering.  This exercise also worked well and again my kids loved this one also.  In this activity, several rocks are placed in a metal can with a top, and water is placed in the can.  The kids observe that clean water is placed in the can with the rocks. 

Next, place the top on the can and have the kids shake the can for a minute or so by counting to 60 or using a clock.  Once done, open the top, and voila:  instant weathering!

The kids can instantly see that the water is no longer clear and that particles of rock were "weathered" off the bigger rocks.  To be clear, I put different types of rock in there including a piece of brick.  The red color is from the brick.  Have the kids record their observations on the data sheet, and have them set the can aside.  With time, and you may have to leave one for while to have this happen, I did not time how long this process took, but you will end up with clear water with sediment at the bottom.

This experiment is also a keeper.  Plenty of action, something to learn, and good, clear results.

The next experiment I did was glacier erosion.  In this experiment, which was written up in the teach engineering exercise, you are to provide the students with ice cubes, balls of clay, and some sand.  First, the students are to flatten the balls of clay into a pancake, then take an ice cube and rub the ice cube over the clay and observe what happens.

The result is that not a lot happens.  The clay is cold and wet, but that is about it.  The students should feel the ice, it should be smooth as well as the clay.  Next, have the students put a bit of sand on the clay and repeat the process. Have the students feel the ice cube.  It should be rough from the sand rubbing it, and then have them brush the sand off the clay and observe it.  Now the clay has lots of little pits in it.

This experiment also worked well.  I will use it. 

Next, I have to figure out what my fourth station will be.  I am thinking of getting tubs filled with soil and rocks and having the students water it with watering cans.  They can then observe the erosion.  In other tubs, I can have soil with grass growing in it, and they can observe that little or no soil washes off that pile.  I will do this experiment later today or tomorrow and take photos to post them.  In the meantime, I have to produce a write up for all the teachers and the volunteers so they can read background on what the students should learn from each experiment, what questions they should ask the students, and include a data sheet so that students can record their findings like real scientists.  I will post these sheets so that you can accesss them if you like.

In the meantime, I have asked some volunteers and teachers to write about their experiences with the program which I hope to post later in the week.

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