Reach for the Sky

Today the 5th graders built skyscrapers.  I found this fun activity in the teachengineering.org website, in an activity called Newpaper Skyscrapers.  It is accompanied by class material, but I found that material a bit lacking, but it does have great links to other web sites.  One link I used was "Building it Big" on the PBS site.  It is a great help for learning more about skyscrapers and a good overview of some of the ideas behind the building of them.  On this site they talk about geometry, loading and have photographs of some of the most famous skyscrapers.  There is also a great site called skyscraperpage.com which has some great illustrations of big buildings all over the world and their height.  The PBS special did not have the Burj Khalifa in it, since the program predated its construction, so I got most of my information about the world's tallest building from its web site and from the skyscraper page.  The Burj Khalifa, by the way, is more than 2 times the height of the Empire State Building.

First, I gave a short overview of the history of skyscrapers, and a brief introduction on how they stand and how they withstand wind loads.  The major types that I covered, as shown in the teachengineering page were stone towers (B.C. onward), Gothic Cathedrals (1200's to 1600's) especially noting Notre Dame Cathedral and the flying buttresses (which of course was thought to be a hilarious term by the fifth graders and elicited giggles every time I used the term buttress), the Home Insurance Building (1880's), the Empire State Building (1930's), the Sears Building (1970'), and the Burj Khalifa (2011).  Each had a concept to get across.  The towers illustrated stout stone walls bigger at the bottom than at the top.  With Notre Dame I discussed the flying buttresses which held up the walls from the outside so they would not be pushed out from the weight of the ceiling.  I showed the idea of the reinforced supporting core for the Empire State Building, which is also a three dimensional grid of steel beams.  With the Sears Building I showed them the hollow tubes that surround the perimeter to provide support, and finally with the Burj Khalifa we discussed the reinforced center support supplemented by the idea of buttressing.

Next, I gave them 4 sheets of newsprint and 12 inches of tape and let them work on building their skyscrapers.  They were to build a skyscraper that could stand on its own without being taped to the table, and then withstand a wind load: a big breath blown on the tower from an arm's length away.

It is fascinating to watch how the students work together, or not, and how their minds think.  I worked with 5 classes today.  In the first three classes, not one group used the cone.  In the fourth class, several groups used a cone, but that may be because my son saw one of my designs that I quickly made just to test out the exercise.  My design used succeedingly smaller cones to attain height and stability.  However, I only obtained 28 inches of height in my quick design.  Another interesting thing to note was that the students tended to put the smaller tube inside the larger tube and then taped it to the larger outer tube.  None of the students stacked cylinders so that they were supported by the one below rather than just the tape.

The most successful designs used flying buttresses that the students made of rolled up paper and attached to a paper base.  The flying buttress designs reached heights of 32" and 50".

The most successful design of the day was a tripod design which attained a height of 50 1/2 inches.  This design had the most stability of any of the designs.  It used three rolled up cylinders which fit in the base of another cylinder to achieve its height, a very elegant design by the students!

All of the students had a great time, and wanted to stay and work on their designs longer than the allowed time.  That for me is a success, along with the fact that they did learn a few things today.

Slinky Waves

Recently, EaSiEE as Pi was in the 5th grade looking at waves.  One great way to show a wave is to use slinkies.  Everyone loves playing with slinkies and they make looking at certain types of waves visually possible.  The 5th graders had just finished studying the rock cycle, the Earth's interior, and plate tectonics.  Earlier in the year they studied sound and light.  So, I decided we would look at waves which would relate to all three of those subjects.  With the help of books and the internet I came up with four stations for the students to rotate through:

1.  Making waves with strings and ropes
2.  Making waves with a slinky
3.  Making nodes and anti nodes with a slinky on a string
4.  Earthquake impacts and characteristics

Before starting, I had to get a couple of slinkies and build some devices for the stations.  I found the slinkies at Toys R Us.  They had the metal versions and the plastic one.  I bought several of the large metal versions and one plastic slinky.  The plastic ones are not really good for demonstrating wave propagation, so make sure you get the big metal ones.  I will explain why I bought the large plastic slinky later in the description of the earthquake station.

In the first station that I listed above, we used different types of string a rope and let the students generate waves.  I used light weight string, elastic string, and a light weight rope.  The elastic string was able to generate the waves with the most nodes.  If you look carefully at the photo below, you can see the rope in the middle with some waves.  This was a popular station and one that I have seen in books and one the internet.  This experiment I looked at the book Making Waves by Bernie Zubrowski.  What we found is that it is very hard to make waves with a student at each end moving the string.  It works better if one person holds the string or rope steady and then the other makes the waves.  The idea was to try and make one wave, then two, then three, and then to make as many as you could.  The idea was for each student to try and make waves with each material so that they could find out which material allowed them to make the most waves. 

Another station that was popular was the slinky station where we had the students make a P or pressure wave with the slinky.  You have one student at each end of the slinky, and have them back up so they have the slinky stretched out quite a bit.  Then as you can see below with the student on the right.  Have them cup their hands, then strike their hand with the other hand to create the pressure wave.  When I did the demonstration for all of the students before we started, the kids all oohed and ahhhed.  I was surprised that they would be so excited seeing the wave in the slinky, but I have to admit, it is pretty cool!  I also had them produce S or shear waves on the floor.  If you have them make S waves with the slinky in the air it often gets out of hand and results in very tangled slinkies.  You can see a great visual graph of P and S waves at the Purdue University site.

One internet source which is a great help in finding fun hands-on activities is the Exploratorium Snack page.  The activity I used was "Slinky in Hand".  I set up a slinky on a fishing line that was tied between two chairs.  With the slinky you can do some interesting things with compression waves.  I used a 10 pound line, although the instructions said use a 20 pound line.  I think a good thick line is indeed needed.  The first class broke the fishing line in the first few minutes.  I then tied a thin cotton string to the chairs and used that.  However, the monofilament line is better because it has a lot less friction than the string.  From the series of photos below, you can see how the students can make pressure waves with the slinky by either moving their hands toward each other in a clapping motion, or moving them together in sync.  However, we found that moving together in sync is pretty hard, and if you get two people who work well together, they can act as if they are sawing a tree and get multiple wave forms that way.

For a couple of the experiments showing the earthquakes, you need to attach the slinky's to a small block of wood.  That setup is described on a website about Earth Science at Purdue University.  If you look at the Seismic Waves writeup, you can see how to build a couple of the devices that I used.  I show a photo below of drilling a hole into a block of wood.  I then used screws and washers to secure the last slinky link to the block of wood, and then built a little house per directions on the website.

This is a photo of the final device in action.  A student is generating a wave and shaking the building and you can see how it is leaning to the left as a result of the "earthquake".

In this earthquake station I also had the metal and plastic slinky's taped together to show how the waves propagate differently through different types of material just as a earthquake would propagate through different types of rock.  This device works quite well.  It also works well to have the kids put it on the floor and generate S or shear waves and see how the propagate differently in the metal vs. the plastic.  This was a popular station.

Overall, I think this set of experiments worked well.  I think I would do a little tweaking.  I think I would use a set of whacking balls.  You can use marbles and string, but buying a set of these balls, called Newton's cradle, would be better.  They show how an seismic P waves can propagate through the earth.  

Another  experiment I might add would be to set a slinky on a piece of sandpaper and have the students move the paper quickly about 6 inches and see reaction.  You can also join two slinky's together for a taller building.  I found this experiment in Janice Van Cleave's book Earthquakes.  

Fun with Roller Coasters

We had planned to have a fun science/engineering day back in December just before winter break with the 3rd graders.  But a bug struck our family and had us down and out for the two weeks before break, so I had to cancel this session.  I spoke with the teachers and we decided to go ahead and use this one out of sequence for our session this week.  What a great time the kids had!  They all proclaimed that this was their favorite activity we have ever done (which is saying a lot since I have been doing science with these kids since kindergarten!).  I used a writeup from teachengineering.org called Building Roller Coasters.  The grade level rating on this exercise is grade 7, but the third graders did great with this activity.  I have also seen something similar written up in Exploratopia (pg. 155).  Both activities use pipe insulation cut in half.  Each team of three was given a cup with a glass and a steel marble, a 6 foot piece of pipe insulation, 12 inches of masking tape, a pencil, and a scoring table.

Roller Coaster Scoring

Roller Coaster Features	Points	Your Design
Height	1 point / 12 inches
90 degree turn	1
180 degree turn	2
270 degree turn	3
Loop	3
Corkscrew	4
Each marble in cup	3
TOTAL POINTS

We talked a bit about potential and kinetic energy, asking the students if they could explain what each meant, and we also talked about acceleration and deceleration.  We then let them go build.  The most points awarded was for a corkscrew, which is the most challenging to build with the six feet of pipe.  Here are a couple of examples of corkscrew designs that worked.

The most popular design by far was the loop.  It also resulted in some good learning, too.  One group in particular was struggling with their loop.  The marble was making it about 2/3 of the way up the loop and falling out.  They couldn't figure out what was wrong.  I sat with the group and started asking them questions:

Why is the marble falling out?

          Ans:  It is not going fast enough

How can you help it get up the loop?

         There was a bit of discussion among the group, I hinted that there were a couple of solutions, so finally they decided to make the ramp or beginning of the coaster higher.

They tested it again, and it made it up a bit farther up the loop, but was still dropping out.  We discussed the problem some more, but they didn't have enough track to make the coaster any higher.  After more discussion among themselves and some gentle hinting on my part, they decided to make the loop smaller.  

Voila!  It worked!

Another group that had a valuable lesson was the group below.  They built a loop with a 90 degree turn.  I asked at the end of the session if anyone had had any problems to overcome and they said yes.  They first had the track flat and the marble flew off the track.  After some trial and error and thinking on their part, they realized they had to bank the track to get it into the cup!  Good thinking girls!

The biggest challenge of the day, besides the noise (which was all very joyful), was keeping some of the groups from changing their design constantly.  Some groups felt that they had to try every possible design and in the end had nothing to share with the class.  I tried to get the groups to experiment, decide upon a design, get it working and stop to share with the class.  A couple of groups just couldn't stop experimenting, they were having too much fun!  The other challenge was that a couple of groups just wanted to get the marble down the track with no twists or turns, so they needed a little encouragement to try new things, and step out of their comfort zone.

This was a great experience for all of us, students, teachers, parents, and me!

Potential and Kinetic Energy for 4th grade

In January, we went in and worked with the fourth grade on an experiment from teachengineering.org called Falling Water.  In this experiment, you take a straw, a meter stick, colored water, and some paper.  The idea is to test that a water drop falling from 90  cm has more potential and kinetic energy than the same size drop falling from 30 or 60 cm.  This idea is tested by dropping the same amount of water from three different heights.  We chose the heights of 30, 60 and 90 cm.  We marked the straws 1 inch from the bottom and the students tried to get the same amount of water for every test.  We had groups of three and four students run the experiment as a team.  Each team member dropped water from each height.  They then measured the diameter of the water drops and recorded them on a table.

Here are some students dropping the measured water from 90 cm.  You can see the measured amount of water contained in the straw.  It is a stretch for the students to reach 90 cm from the table top, so we suggest that they run it on the floor.  The second photo shows the water after the drop.  You can see it makes a nice large circle on the paper.

The students circle the drops with ink, then record the data in a table.  You can see the paper with the drops circled on the left below and two team members filling out the data table.

The students have a great time with this experiment, and overall the experiment works the way it should with two exceptions.  One, each team member makes a drop at each height.  Some teams are very careful and meticulous and their data is very tight.  Other team or team members may not be as careful about the whole process.   They may not get the same amount of water in the straw each time.  They may have problems with using the straw and keeping the water in, or they may not trelease the water from the straw with it straight up and down and may release it at a slant.  If you drop the water with the straw slanted you get a nice big oval rather than a circle, and then it is hard to pick a diameter.  The other thing that can happen is that some team members are very careful and one or two may not be as careful with the process.  In this case, you will get two good data points, and one or two that may be way off.

Even if the results are not great for every team, it presents a learning opportunity.   We discussed why some of the data point are off.  The table that the students use with sample data is shown below.

	Water height at 30 cm	Water height at 60 cm	Water height at 90 cm
Diameter of first splash	70 mm	68 mm	65 mm
Diameter of second splash	45 mm	65 mm	60 mm
Diameter of third splash	49 mm	57 mm	66 mm
Average Diameter	55	63	63

The writeup asks that the students calculate the total of the drop diameter and the average.  First of all, the fourth grade has not studied averages yet, but some of the more advanced students can do this.  However, I disagree with this method for graphing the data.  If we use the data above, then the graph that results is shown below.  This graph shows that the drop size increases from 30 to 60, but not from 60 to 90.  So, the students could conclude that the height of the drop doesn't necessarily result in a larger circle.







However, if we have the students plot each data point, then we know there are some problems with the data.  We can see right away that the first set of data show that the drop size for two of the students is about 45 to 49, but the third point shows a drop size of 70 mm.  Right away, the students can see that something is not quite right.  It could be that one of the students used too much water, or slanted the straw and then measured the resulting oval with a very large diameter.  In the 60 cm drop, we have one data point that looks correct, but two that look a little large.  The third set of data at 90 cm looks about right.  Having the students plot all of the data rather than just the average shows where there could be problems with the experimental method, and opens up the discussion about how to run careful experiments.  If a student team is very careful, they should see plots such as the one shown for student 3.   Most of our students groups had such plots.






Overall, this is a great experiment, and one that I would recommend.  The students love it, and find it straightforward to do and results in a lot of good discussion about experimental method and the care that scientists must take with experiments as well as discussions about potential and kinetic energy.

Saving Humpty Dumpty

The kindergartners study nursery rhymes, so the teachers and I discussed what kind of activity we could find that would tie in.  We came up with the Humpty Dumpty Safety Device.  If Humpty Dumpty had been wearing one of these designs things might not have been too bad!

Within our 45 minute session, we told the children that they must design a safety device for Humpty Dumpty given the set of parts that were provided.  The parts can vary, but this year we included:

• a straw
• a paper clip
• an index card
• a 4x4" piece of bubble wrap
• 2 cotton balls
• 6 inches of pipe cleaner
• 3 or 4 pieces of styrofoam peanuts
• and 12 inches of tape.

Last year we included a small cup, and none of our hard boiled eggs cracked.  This year I decided to replace the cup with the index card.  The results did change.  

The designs varied to some degree.  Some groups were more engaged than others.  Often the kids just wrapped up the egg in some form of another without real thought to how to protect the egg.  One of these designs is shown below.  Some of these groups only used a few of their materials.

Other groups used all of their materials and had an approach of putting everything in a somewhat haphazard manner.  Sometimes these designs worked, sometimes they didn't.

 Other groups spent a bit more time thinking about how to protect all of the egg.  The two designs shown below are built sort of like canoes with protection on all sides.  Depending on how well the sides are protected, this design worked reasonably well.

Another common approach was to build something that looked like a paper can.  Most of the time this design was not so successful.  The kids tended to protect the top and bottom of the egg, but neglected the sides which cracked in the drop.

The photo below shows our most innovative design.  The kids wanted to design a parachute.  I had my doubts about its success, however the egg survived with no cracks!

On average of the six groups in each class, only two were able to prevent Humpty Dumpty's demise, and the rest were cracked to some degree.  The kids were all good natured about it, save one girl who did cry when her team's egg was cracked.  However, having the boys cheering for cracked eggs probably did contribute to this situation.  In most classes, the kids cheered for all the teams and were good natured about the whole process.

The wall we used was built from card board bricks and taped down.  We rolled the designs off, and then opened them up to see how Humpty Dumpty fared.  We used boiled eggs, which did cause a few kids some confusion.  Those kids that had not had experience with boiled eggs were confused as to why the yolk didn't run out when they were cracked.

The last innovative design I want to show is the one below.  These kids built a type of spring out of the pipe cleaner and the straw.  The concept worked well, and kind of bounced on the floor, and prevented the egg from cracking.

 Overall, this activity went well.  I think next year I would eliminate the peanuts in favor of a different soft material.  Some of the kids could not help buy shred the peanuts, and I spend 15 minutes or so cleaning up the mess afterwards!  So, I would recommend forgoing peanuts.  As in all of the activities, it is a lot to pack into 45 minutes.  However, this is all the time that their schedules allow.  If we had more time, we would have the kids redo their designs and try again.  We did discuss how engineers design and test and redesign all the time.  That is part of their design and learning process.

The kids love this activity, and it is one that we will keep doing.

Bird Beaks

This year is quite busy.  I am now running sessions for all six grades (K-5), so I find it hard to take photographs while running the sessions and on a day to day basis, just getting stuff written  down for the blog.  So I apologize being so slow.

We ran a Life Processes session for the third grade a couple of weeks ago.  This is the second time I have run this session.  It certainly went better this year than last.  Here is the relevant section of the third grade standards requirements for Virginia:

The student will investigate and understand that behavioral and physical adaptations allow animals to respond to life needs. Key concepts include

a)     methods of gathering and storing food, finding shelter, defending themselves, and rearing young; and 

b)  hibernation, migration, camouflage, mimicry, instinct, and learned behavior.

I divided this activity into three parts.  There are similar exercises that you can find on the web:  1) Fetch!  "Eat Like a Bird" and 2) The Wonder of Birds.  First, I put out gathered materials that could be used as "food" for the birds.  I try and find what I have around the house, but used:  marbles, small rubber erasers, various sizes of dried beans, rubber bands, puffy balls, small rocks, hacky sack balls, plastic eggs, jar with tubes of water, and old logs, and seed pods.  I scattered the food and put some of the food in a tub of water.

We had the kids divided into groups of four.  Each group was then given an assigned "beak".  The beaks included: fork, spoon, chop sticks, toothpick, water dropper, and a straw.  For the first part of the activity, the kids were directed to come one person per team at a time and get one piece of food.  They were not to try and spend much time, but come up, get the food, and "fly back to their nest" with it.  Each team member had a chance to go.

We then discussed how things went and they were to try and decide what kind of bird their beak might represent.  The general consensus was:

fork:  water bird such as a spoonbill or flamingo that filters its food
spoon:  water bird that scoops its food such as a duck
chop sticks:  can be various birds such as a crow, blue jay, etc.
toothpick: small bird such as a small woodpecker or nuthatch
straw:  not a very effective beak, no real correlation
water dropper:  hummingbird

We then talked a little about how beaks were adapted for specific environments.  Next, we gave the kids an opportunity to design their own beaks.  They could select from the materials provided in the first activity, plus they could use rubber bands.

Once the kids had build their beaks, we reran the previous exercise with their own beaks. 

In the third part of the activity, we cleared the table of most food and left just a few things that the kids tended not to try and pick up and ran the exercise one last time.

We then discussed what happened.  In general, the kids tried to design a beak that allowed them to pick up the most diverse sets of food.  They all tended to pick up things out of the water first.  We then discussed what implications it had when we removed much of the food.  The answers to the food removal causes were:  seasonal changes, weather changes such as massive storms such as hurricanes, droughts, and a dying out of a food source due to environmental changes.  Finally, we discussed what strategies were available to the birds to overcome the food scarcity.  The strategies that we discussed were migration and adaptation.

The kids loved this exercise, and I think they got a lot out of it.  If you are interested, contact me and I can send you the writeup.

Goop by any other name....

Last week I started our round of engineering and science activities for the year.  I am kept busy this year with one to two sessions each week now that I have grades K-5 participating.  Recruiting volunteers remains a challenge...But onto the important stuff.

We started third fourth out this year making homemade silly putty.  I found three different recipes on the web and decided to let the kids test them out to find out which worked the best.  My intention, you know the idea, "the best laid plans..."  and "the road to h___ is paved" with good ones, did not result in what I had hoped.  Making the transition from teaching college kids to elementary school kids is challenging.  I forget how much they can take in at one time and still tend to bombard them with information.  In any case, I had intended that we test the three different formulas to see how they performed, and how well they mixed up.  I think the kids just got that they could mix up the putty and have fun and I am not sure they got anything out of it other than that.

I had intended that the take a logical approach to making and testing different formulations and scientifically decide which was better.  Control of the mixing and product was difficult.  Let me explain why.  Here are the three formulations we used:

	Formula A (red)	Formula B (green)	Formula C (blue)
Glue	1 teaspoon	1 teaspoon	1 teaspoon
Water	1 teaspoon	2 teaspoon	1 teaspoon
Borax Solution			1 teaspoon
Borax powder	1 teaspoon	2 teaspoons

When I did this at home I did not use food coloring.  I would definitely suggest you use the food coloring.  If you don't all the samples are white and it is really hard to tell them apart.

It makes for a bit more mess, but it is easier for the kids to keep up with everything.

First, we talked about safety.  Borax is a really safe detergent booster, but if ingested, a lot of it could make you sick.  There is that occasional child who likes to taste things....  We then talked about the attributes of silly putty.  The commercial silly putty is very stretchy, bouncy, and can take up images from newspaper really well.  I told them that these are the things we wanted to test for in our formulations.  I told them that we were looking for the best recipe for them to make again and to recommend to their friends.  Finally, I then asked the kids if they knew what a chemical reaction was and how to look for it.  They had covered this in class, and had several suggestions on looking for reactions:  blows up, bubbles, fizzes, changes color, smokes.  Very few had the idea that the mixture could give off heat.  I suggested they look for changes including heat. That of course is what happens when you mix the water and borax, you get some warming.

I then had the kids mix up the samples in the following order:  first mix the water and borax until it is really mixed up, last, add the glue and mix some more until it begins to ball up.  You can add the color at any time, but an adult should drop in the color.  We used two forms of borax: straight powder and a solution, which was 2 tablespoons of borax mixed with 1/2 cup of warm water.  The mixing process is a bit messy and can vary a LOT from child to child.  We did have some issues of the formulas not coming together or being too crumbly.  One child would have a great mixture, and at the next table the same formula would look totally different.  

Once the formulas were mixed and rolled into balls we tested them.

	Formula A	Formula B	Formula C
Bounciness	cm	cm	cm
Imprint Retention	sec	sec	sec
Stretchiness	cm	cm	cm
Pull
Ink Transfer	good  fair   poor	good  fair   poor	good  fair   poor

Again, as in the mixing of the formulations, the testing accuracy varied greatly.  I had the kids divided into teams of three and were supposed to work together the make the test the various formulas.  However, team work is hard for them.  They tended to work independently, but they had to help each other with some of the tests.

Here is a list of the tests we performed:

1. Form the putty into a ball and see if you can bounce it.  Using a meter stick, see how high the ball bounces when dropped from 1 m. high.  Record on Activity sheet.  Do this for each formulation.
2. Take your pencil or handle of spoon and make an imprint in the ball.  Record how long it takes for the imprint to disappear.
3. Roll each ball into a 2 inch rope and slowly pull the rope and record how far it stretches before it breaks.  How far can you stretch it?  Measure with meter stick.
4. Quickly pull each formulation and record the results.
5. Flatten into a pancake, using a sheet of newspaper, test how well each formulation picks up the ink off of the newspaper.  Can you read it?  Record the results.

There were a couple of problems with the testing.  Imprint retention was VERY subjective.  The idea was to let the students see that silly putty acts a bit like a liquid in that with time it slowly moves to take the shape of its container like a liquid.  Then, if acted upon quickly like in the pull test, it will break more like a solid.  I believe the kids were too focused on playing with the putty to think and compare their results.  

The stretch test was a bit easier to perform if the kids followed directions, which of course many didn't. We laid the two inch rope of putty on a meter stick and slowly pulled.  Overall this test went well.

Finally, I had newspaper laid out for testing transfer of ink.  None of these formulas really transferred any ink to speak of.

In the end, the kids were not able to detect a clear winner on which formulation was the best.  It was so dependent on how well the kids measured and mixed that we didn't really take away what I had intended from this lesson.  I am not sure how I would change this for next year.  

As for me, there was a clear winner in the three formulations shown above.  The one made with the borax solution was a bit messier to mix, but in the end was more consistent than the other two formulations.

One thought for next year is to let the kids decide how to formulate the putty using the following table:

	Control (red)	Formula A (green)	Formula B (blue)
Glue	1 teaspoon	1 teaspoon	1 teaspoon
Water	1 teaspoon	x teaspoon	xx teaspoon
Borax Solution	1 teaspoon	y teaspoon	yy teaspoon

One thought for next year is to let the kids come up with a variation on the control formula and use the borax solution approach.  I have not tested this procedure, but will have to look into it.

In any case, the kids had fun.  Half the battle at this age is to get them to have fun with science and engineering and to inspire them to learn more.  In that light, the activity was a great success.