Increasing Strength

After our investigations yesterday in how we could make a material stronger, we continued today by looking at how we can make a structure stronger.  We learned about two supports that can be added to a structure to help it support a heavier load.  A strut is a beam or bar that is used to stop two parts of the structure from being pushed together, and a tie is a beam or bar used to stop two parts from being pulled apart.

To help us understand how struts and ties work, we conducted a bit of an experiment.  Students received 12 straws and some pip cleaners to build a basic cube structure.  They were then asked to place a light weight book on top of the cube.  Next they were to place objects one by one onto the book and record what their structure held.  Most students found that their straw structure couldn't even adequately hold the book!

The next step was to alter their cube structure to make it stronger.  Students received 8 more straws and more pipe cleaners.  With these straws they could be used in any way that they wished -unlike with the first set, they could bend them, cut them, etc.  

Students tried adding struts and ties to different parts of their cube.  They then repeated the strength test.  They replaced the book on top of the cube and placed objects one by one.  When the structure failed, they were to record what the reinforced structure held.  Many students were successful in making their structure stronger.

How Can We Make a Material Stronger?

Today in Theme Studies, we looked at a particular material, a piece of white paper.  As a building material, paper isn't very good.  It's not very strong, doesn't hold a lot of weight, and rips easily.  So we brainstormed ways that we thought we could make the paper stronger.  

We came up with two main ways.  We could put several pieces of paper together to make the paper thicker and we could fold the paper.  With these two ways in mind, students tested out our ideas.

Each student received several pieces of paper to use to try out both methods.  They were allowed to choose the type of glue they wanted to use (white glue or glue stick), and they were allowed to cut the paper if they wanted more pieces.  They were instructed to find out two things.  They were to see if doing these two things to the paper did make it stronger, and they were asked to see if they could figure out which method make the strongest paper.  We decided as a class that an easy test to see the strength would be to rip the paper.

After our experiments, we came to three conclusions:

1) Folding paper increased its strength.

2) Layering and gluing paper increased its strength.

3) Folded paper was stronger than layered paper.

Following this activity, we briefly discussed whether we could apply our new knowledge to other materials as well.  For example, would nailing several pieces of wood together be stronger than a single board?  We decided together that this information was useful when working with other materials as well.

Increasing Stability

Yesterday during Theme Studies we examined how well objects remain standing.  We began by trying to balance our pencils on our tables.  Some people were successful and some weren't.  After discussing why this might be, we then began examining just how stable even the standing ones were.  Even though some pencils could stand up, none of them were very stable.  We then looked at two different sized paper tubes, a shorter one and a longer one.  Students were asked to decide which tube they thought was more stable.  Almost everyone chose the shorter tube.  Even though they both would tip over easily, the shorter tube took more strength to do so.  

Today we reexamined our tall paper tubes.  Our goal was to do something to them so that they would be more stable.  Students were given supplies to use and were provided with the rule that they could add to the tube, but they could not take away from it.  They were then left to explore how they could make the tube more stable.

Each pair was successful. however some were more successful than others. 

We came up with a list of the strategies that we used, and discovered that most of them were similar.  Most pairs either made some sort of foundation for their tube, or increased the weight or size of the bottom of the tube.  Both two good ways to increase stability.

Exploring The Living Prairie Museum

This afternoon we went on our field trip to The Living Prairie Museum.  While we were there, we learned lots of interesting things about Soils!

After walking from the school we had a chance to sit down and learn about what soil is made up of, why soil is important, and what we can do to keep our soil safe.  It was an interesting presentation and we all learned a lot!

Next, we learned how the size of soil particles affects the speed at which water passes through the soil.  Three volunteers came up to help us as we poured water into each container of soil and counted how long it took for the water to begin flowing from the bottom.  With sand it was only 2 seconds, top soil 3, and we counted all the way to 30 seconds for the clay pot, but no water came out!

After the presentation, we had about 10 minutes to explore the area inside.  There was a lot of neat things to see, including an area which showed us the prairie at night.

Next, we divided into two groups.  Each group had a chance to work on four different soil experiments.

We sifted soil to see the different materials it is made of.

We learned to tell if soil contained clay by the ribbon test.

We learned all about the two different types of composting.

We used a magnifying glass to see what different things were found in a soil sample.

Before we returned to school, we had a chance to tour the prairie reserve, filled with natural prairie grasses and plants.  We saw many native plants to the area and the largest ant hill we have ever seen!

It was a fun-filled afternoon and we all had a very good time!