Friday, June 29, 2012

BioX Kids Day 2012 - Elbows Booth Recap

Holy Moly - I never thought I'd get around to this posting (I've been running nonstop since the event).

I had so much fun at Stanford BioX Kids Day 2012, on June 15th.

Here I am in my booth slightly before the event started.  They even gave me a super cool mad scientist shirt (which you can't really see, but trust me, it's awesome).

Anyways, that was the last time you'd be able to see me over the crowd.

It was so nice of the event coordinators to offer us ice cream (it sat on the corner as shown in the pic below for 2 hrs before I tasted the ice cream soup and threw it away).  I was explaining the elbow model to over 150 young kids over the course of 4 hours.

I had an awesome helper, Steve, shown behind me

Here's the original post for the elbow lesson I did, modified slightly to make it easily understood by younger kids: Biomedical Engineering Elbow Modeling (please note, that the idea for the project is in no way my idea see pg 16 of this lesson for where I found the idea).

How the lesson went (and increased in complexity depending on the age and interest level of the kids - which ranged from 2-18 yrs old):
  • I asked to see the kids' elbows and then asked how many elbow each person has.
  • I asked if they knew what muscles are and if they can show me their muscles on their arms
    • I then tried to relate their muscle size to Popeye (and encouraged them to eat spinach), but apparently Popeye is pretty irrelevant nowadays.  Sad.
    • I asked if they knew the names of the big muscle they were showing me (biceps).
  • I asked if they could bend and straighten their elbows.
    • I informed them that muscles only pull, which is a lot like what string does.  Have you ever tried to push something with a string?  It just doesn't work.  Period.
    • So if the biceps are big when you bend your elbow, what muscle is big when your arm is straightened?  This is a hard question (luckily, I have pretty large triceps for people to poke - they aren't super big in most little kids).  You can also talk about how many heads each muscle has for the older kids (biceps = 2, triceps =3).
  • Biceps bend the arm and triceps straighten the arm, all while pulling - if anything, this was a good take home message for the kids.
  • Now that we established the ground rules (biceps bend, triceps straighten), we assembled our elbow model:
    • Due to budget limitations, I went to the 2-ruler model - 1 ruler for the upper arm (humerus) and 1 ruler for the lower arm (radius+ulna).
    • There were two big holes at the end of each ruler.  Don't use the bigger holes (unless you find bigger brads, but I unsuccessfully searched for bigger brads).
    • The best holes to use for brad insertion were around the 2 inch mark.  Using a brad to connect 2 rulers made a simple hinge joint.  At this point, I demonstrated that it can open and close when I push on it.  Keep it open in an "L" shape.
  • Our model is missing the most important piece of the lesson (ie. what bends and straightens the elbow?). I made a brief introduction to the term "tendon," pointing out that tendons connect muscles to bones.  If you want to see a tendon, look down toward your heels.  Your Achilles Tendon connects your calf muscles to your heels and is a very tangible example of a tendon.  We have smaller tendons in our arms connecting our biceps and triceps to our arm bones, but it's all inside our arm and we can't see it.
    • To model a biceps muscle with a tendon, double knot a piece of string to a paperclip bent into a hook shape.
      • Attach the tendon to the lower arm, around the 10.5" mark on the lower ruler, and string the string through the 10.5" mark on the upper ruler (don't tie it or knot it since you'll be pulling on it).
      • Have the kids pull on the string.  Sweet, they just bent their elbow.
      • For the older kids, ask them if they could point in the direction of the force the muscle is generating (along the line of the string).
      • Now can they straighten their elbow?
    • To model a triceps muscle (another string + paperclip hook) is a little more tricky since you want it to still attach to similar locations in the lower and upper arm, but the force is supposed to be directed downwards (opposite-ish of the biceps muscle).
      • The trick here is making a joint capsule (lower friction environment) by directing the string through a paperclip which you stick on the back of one of the rulers.
      • Attach the hook to the lower arm around the 9" mark.  Thread the string through the paperclip on the end of the ruler (the end closest to the brad), and then thread the string through the upper ruler around the 9" mark.
        • At this point I want to point out that you should be holding your elbow horizontally, so gravity doesn't straighten your elbow instead of the triceps.
      • While the elbow is bent, have the kids pull on the string that is threaded through the 9" mark on the upper arm (the "triceps").  It should straighten the elbow.  If it doesn't, check that the hook on the lower arm for that muscle is directed downwards.  Then check to make sure your string isn't getting caught up with friction somewhere else.

I made a lot of these for the little ones, older kids, 5+, can do it on their own
Super cool elbow makers:

I held while they pulled their muscles
Father and son, learning about elbows together. 

**Note the exact location of the holes may vary depending on what kind of ruler you purchased (ie. adjust 10.5" and 9" as you see fit).  Even my two purchases from the same vendor (a few months apart) varied. We used these rulers: Charles Leonard Inc. Ruler, 12 Inch, Wood, 36 rulers

Wednesday, June 27, 2012

Shake Tables in the Park

Thanks to Pepsi Refresh, I was able to build my shake table and bring it and the building supplies to the park.  I decided to up the building material limit to 100 toothpicks to see if 12" could be obtained and it was!  I decided not to

We had a lot of new faces join us this week.  We had tons of fun.  Here are just a few pics of our fun times.

Our friends learned about strong shapes and started building strong and tall!

Some friends tested their designs at each new level.

He's doing a happy dance that his tower was over 12 inches and it stayed longer than 20 seconds on the shake table.

Showing off his masterpiece.

J decided to go more jungle gym than tall tall tower.

Good building by a good friend.  It too survived 20 seconds on the shake table.  Good job, buddy!

The Leaning Tower of Pisa.  It didn't start this way.  On a fun note, a random kid stopped by the table after this tower's designer had left and asked to keep this tower.  I guess it had personality.

This Saturday will be our last official Pepsi Refresh sponsored project in the park.  We're building Lego race cars and sending them down ramps of different heights and different landing surfaces, learning about coefficients of friction.  It'll be Saturday, June 30, 9:30a-noon.  Please RSVP using the email address over on the sidebar <=== - and I'll give you the location.

Tuesday, June 26, 2012

Shake Table Structures - Preschool

I took my homemade shake table to J's preschool for the 4-5 yr olds to do science.  I wanted to try out the tables and building materials before bringing it to the public with science park day.

Here's how my preschool visit went:

Some kids experimented with different shapes before deciding what to build:

This would be a good point to demonstrate the strength of the shapes.  Triangles stand tall and don't collapse when you push down and them.  Squares collapse under the weight of you pushing down on them.  Ask which shape they'd rather have for their houses.  You can also ask why roofs are triangular shaped.

They had some good building going on.

They learned a little about measuring during this lesson.

I gave them 50 toothpicks and hoped they could make 12 inches tall (no limit to the marshmallows since the more they are handled, the more squishy and less reliable they get).  The tallest structure we got was 7".  This was our winner who was the tallest and lasted 20 seconds on the shake table.

**Don't worry if you don't have the time or resources to make a fancy shake table.  You can make an easy shake table with two pieces of cardboard, 4 same size bouncy balls, and 2 rubber bands.  See Raft's Shake Table on how to construct the simple shake table.  Marshmallow structures work for those shake tables too.

I'll post my lesson that preceded the shake table structures in a few days on the layers of the earth and a brief discussion about plate tectonics.  They were surprisingly interested in the brief lesson and game I had.

Friday, June 22, 2012

Tada! Homemade Shake Table

Isn't it so pretty?  I am so excited about completing this shake table lesson plan, as it was a favorite of mine as a kid.  It actually took some engineering thinking to completely enclose it and give me all the features I wanted.  I also got some much needed practice soldering.

Here's what I did:

1. Based my design around the Exploratorium's homemade shake table - mainly a 1.5-3V motor spinning an offcenter weight (wingnuts and washers), with a potentiometer to vary resistance and shaking speed, which runs off of 1-2 D sized batteries.  I kept the same base and shake table sizes, along with the square edge lining.  The top is still attached to the bottom via rubber bands.

The innards of the raised shake table
2. Completely redesigned it to stand on 4 pillars (~3 inches tall), so I could mount the motor on the underside. I super glued milk caps (instead of film canister lids - who has those nowadays anyways?) to the pillars to house the marbles the shake table sits on.
3. Adapted the circuit so it can run off of batteries or AC (plug into a household socket).  For this I got a power adapter that goes down to 3V.  I found a plug for that adapter and bought an extra plug of the same size, which I soldered to a plastic 2 D battery holder.  Since I want to do this in places without running electricity (like the park tomorrow) and I didn't want to waste batteries if I go into schools or do this at community centers, it was an important feature for me to have both options.

4. Added an on/off switch to the circuit.  Who doesn't like turning on a switch and being in control?

On/Off switch + variable resistor (potientiometer)
5. Since I wanted it enclosed, having rubber bands sticking out in the bottom wasn't going to work, so I took small eye screws that came in a wall mounting kit we bought moons ago.  I opened each hook up slightly (enough to insert a rubber band without breaking it).  I mounted four screws on the underside of the shake table ==> one at the halfway mark of each side.  I made sure they were mounted directly under the piece of wood on the end of the shake table.  Four more screws were placed on the plywood base, 3 inches back from each side on the mid-line.
6. The motor was mounted on an extra block of wood I had leftover from raising the table up 3". My husband made a custom mount piece using his 3D printer.
7. For the enclosure, I created a drawing of what I wanted and cut 0.25" thick alder board with the laser cutter in a puzzle-like interlocking pattern.
8. To keep the top from falling down, I super glued small metal L brackets/corners on the side piece which allowed the top to be flat but not glued to it (I want to be able to remove the top pieces).
9. The two sides with electronics on it were fixed to the plywood base and each other via wood glue.
10. The two remaining sides were attached to the fixed sides and each other via cabinet magnets.  I wanted to be able to remove the top and access the underside of the shake table if anything (like the rubber bands or motors) decided to poop out on me.

Then of course Big J and I tried out the marshmallow structures before the kids and successfully made ~12 inch structures out of 40-50 toothpicks.  Mine was taller and was stable on the shake table, buuuut, it collapsed on itself overnight which is fine - it did what it needed to do.  I called it the giraffe (on the shake table below).

Wednesday, June 20, 2012

Straw Rockets - shoot for the moon

I tried to think of a fun game to get the kids to shoot at things besides people for our Rocket Science Day in the park.

I came up with cutting up a few sides of a cardboard box to make the moon, Mars, Jupiter, and some stars. I then hung them from the tree at the park (with the help of my taller husband - it still sucks being 5'2.5" most of the time).  I think it turned out cute.

I had the idea that kids would stand behind a cone (distance depending on their age) and shoot for the celestial bodies.  I arbitrarily assigned each object a couple of points.  The moon = 10 pts, Mars = 30 pts, Jupiter = 40 pts, and the stars = 50 pts each.  If the kids reached 50 pts, they got a small prize.

Straw rockets are made similarly to our homemade rockets (insert link), except that you wrap the paper around a pencil instead of a 1/2" PVC pipe:

1. Roll up part of a piece of paper on a pencil. Tape the paper to itself (not the pencil). 

2. Place tube on straw and blow.
3. What happened? Nothing. Why? You need to close off the tube so the air from your mouth going through the straw has something to press against.
4. Tape off the top of your straw rocket. Shapes to try: flat/rectangle, cone/triangular. You might even try to tape a second piece of paper onto your straw rocket for a proper nose cone.
5. Place rocket on your straw and blow as hard as you can. Did your rocket fly off?
6. Is your rocket missing anything that could help it fly?
7. Try giving your rocket wings. Does that improve the flight of your rocket? Why/whynot?

Troubleshooting your rockets (this is also helpful for homemade stomp rockets):

  • Is your rocket too heavy or light? Add or remove paper material as you see fit (ie. wrap paper more or less times around the pencil/pipe). 
  • Your rocket doesn’t launch or go far. Check to make sure your rocket is well sealed with tape. If air escapes, you are losing valuable fuel. 
  • Your rocket doesn't fly straight. Add wings and fins. If one design doesn’t work, try another shape/design. 
  • Your rocket is boring. Decorate it!

**These rockets are still showing that for every action there is an equal and opposite reaction.

***Note that our friend shooting the moon is blowing on his stomp rocket through an extra PVC pipe.  This made a better straw rocket than a regular straw.

Tuesday, June 19, 2012

Make your own stomp rocket launcher

I'll admit that I love to be a "do it yourself" type of mom.  However, I'm also a very busy mom (who isn't?) with very limited living space (reason # 304 that I sarcastically <3 the Bay Area :-P).  To me, my time and space makes a purchase under $20 worth it, most of the time.

I thought since my blog was created with a goal of not taking chunks out of your wallet for science fun, that I'd give you an alternate to buying a stomp rocket kit (which was recently on sale for $10.50 over the weekend - check with Amazon: Ultra Stomp Rocket, affiliate link, to see if the deal is still good).  We used a kit for our Rocket Science Day in the park, knowing it was going to get a lot of good stomps (it even survived soccer cleats which slipped by us for a few jumps).

The cost of a Do-It-Yourself launcher is ~$10, using parts bought at your favorite home improvement store and ~30-45 minutes of set-up time (if you include going to the store for the items).  I adapted this from homemade rocket launcher, mostly altering sizes since I can't store anything large, and taking into consideration the adaptation from one of the commenters since I couldn't get the bottle cap to stick to the PVC pipe.

Materials: (~$10 if you have PVC glue and pipe cutters already)
-8 ft of ½ inch PVC pipe
-Connecters (all slip fit):
  •          1 – ½ inch 90 degree elbow
  •          1 – ½ inch cross (+) fitting
  •          2 – ½ inch end caps
  •          1 – ½ inch coupling
-1 – ½ inch CPVC transition adapter with male threads
-1 – ½ inch CPVC transition adapter with female threads
-Empty, clean, and dry 2 liter bottles (plenty since each bottle has a limited lifetime of stomps - unfortunately for my family, I gave up my 27 year soda habit).
-PVC pipe cement/glue (note all purpose pipe glue is needed if you select to glue PVC to CPVC adapters – but you might be ok without gluing that part)
-Pipe cutters (optional, but they make life so much easier)

-Cut the ½” PVC pipe into length segments of sizes:
  • 1 - 18" piece
  • 2 - 11" pieces
  • 1 -5" piece
  • 1 - 14" piece
-Dry assemble your launcher to make sure everything fits.

- Once dry assembled, take pieces apart one at a time to PVC cement them in the arrangement as found above.  It’s easiest to take apart one at a time as to not make mistakes.  I recommend not gluing the bottle piece (ie. the coupling to the 18” PVC) to make it easier to exchange 2L bottles when necessary.  I did use special all purpose pipe glue to attach the CPVC male adapter into the ½ inch coupling.
 -Attach the 2L bottle to the adapter piece, slip fit ½ inch coupling onto 18” PVC pipe.
-Take the leftover PVC pipe and cut into ~12” segments.  Use this pipe as the roller to wrap your paper around for your rockets.
-Follow directions on below on how to make a rocket for your launcher.
-Place your rocket on the vertical 14” PVC pipe and stomp/jump on the 2L bottle.  Watch your rocket fly to the moon.

Paper Rocket Instructions:
-Take ½ inch PVC pipe and roll paper around it (we used construction paper).

-Tape the paper to itself (not to the pipe).

-Figure out the best way to close off the top of your rocket.  What do you think will be the best shape? How will you do it?  A cone is a really simple shape to make: take a circle and cut a slit through ~1/2 way.  Then overlap the paper (twisting motion) until the paper forms a cone shape.
-Does your rocket need fins?  How do fins help your rocket?
-Make another rocket of a different size (bigger, smaller, more, or less paper) or with different fins and nose cones.  Note how each rocket flies.

Tada, homemade rocket
These rockets also fit on some store brand stomp rocket launchers.

Monday, June 18, 2012

Rocket Science in the Park

Thanks Pepsi Refresh for the loads of fun we had in a local park Saturday to learning about rockets.  The main lesson was for every action there's an equal and opposite reaction.  Without the nose cone (or the closure over the rocket tube), air will just shoot through the rocket tube and out the top, leaving the rocket still on the launcher (we demonstrated this with a broken rocket).  With the nose cone, there's now a place on the rocket for the air to push on and the rocket flies off of the launcher.  Now the amount of air pressure you create, will determine how high your rocket flies!

If you lightly tap on the stomp rockets like this:

It's not going to go very high (this one barely made it off of the launcher).

If you stand and do a medium stomp, it'll go higher:

Give it a "hard as you can throw down your foot" stomp and you get it about tree level:

But if you really want to get the stomp rockets stuck in the trees (or really really high up in the sky), you got to put your whole body into it and JUMP!!

Which will be met by the reactions of the people watching your rocket fly up into the sky (and hoping they don't have to do a rocket rescue from the trees):

Another fun thing you can try is playing with the angle of launch (making sure it's not directed into traffic, people, or anywhere dangerous, of course):

Which might surprise you where it goes (or maybe not)

I'll post a few lessons this week on how to make your own stomp rocket launcher from PVC pipe (~$10), paper rockets, and straw rockets.  I already posted a lesson on the squeeze rocket launchers which were also part of the fun day. However, I found mini 12oz empty soda bottles are much more resilient to little kid squeezes than small, crumply water bottles.  This find was a major improvement to the lesson.

Also, I was looking for replacement rockets since ours got beat up quite a bit from all of the fun and found the whole manufactured launcher kit to be on sale for $10.50 on Amazon (Ultra Stomp Rocket, affiliate link).  Also, make your own rockets (which offer a load of extra nerdy science-y goodness) which I will post tomorrow or the next day also work on the store rocket launchers too, so no need to buy extra rockets.

Hope the summer is off to a great start!

Saturday, June 16, 2012

Marshmallow Shooters

We were bored one Saturday, so we totally ambushed our neighbor (who was the one kind enough to show us the Transit of Venus) with our family of marshmallow shooters.

Our desires for marshmallow shooters came around 5+ years ago when we thought it would be a fun family past time of Big J and his 4 brothers.  I believe we did buy one at Christmas ~$15 for one of the brothers, but 5 would have been above our poor young adult budget.

We were at Maker Faire last month (I know, I owe a run down on it, but I'm seriously in lock-down mode due to the end of the Refresh Grant) and found 2 shooters for sale for $20.

Big J took a picture of the box and decided to get material to make our own.

Per shooter (~$5 total)
~2.5-3 ft 1/2 inch PVC pipes
2 - 90 degree slip fit (not threaded)
2 - T slip fits (not threaded)
2 - slip fit caps (not threaded)

It would be helpful if you had a PVC pipe cutter (which we had from a previous project).  They are ~$10 (so not super cost effective if you only make 1, but better if you make a family of them).

These are the measurements from our shooter (based on small person (J and Mommy's) hands) - it's very customizable:

3 - 5" (two handles, 1 mouth piece)
2 - 2" (connectors between the handles)
1 - 3" (neck between the mouth piece and the barrel)
1 - 7.5" (barrel of the shooter)

We didn't glue the pieces, which made it super easy to take apart and retrieve lost marshmallows.

Here's what our family of shooters look like:

Minus one for this reason:

Here's how you use the marshmallow shooter:

Insert the marshmallow into the gun

Give a firm, quick blow

Repeat, over and over again.  Hopefully, you don't have this disaster:

If you do, feel free to still use them (or reuse already shot marshmallows).  Just make sure you and your kid(s) know not to eat those ones.  We had a no eating marshmallows rule once we started reusing.

If your marshmallow gets stuck

Take apart the gun and fix it.

We picked the wrong person to pick a fight with.  He had his own marshmallow shooter (~$15 store bought).  Luckily J took it hostage.  Good job J.

He didn't know how to use it, so he got assistance.

This activity has been a big highlight to our summer.

Don't shoot me, I'm just innocently taking pictures!

Hope you have fun with your shooters.

*Sorry for the premature post - I wasn't ready with pictures and hit publish instead of save.  Blogger doesn't have that 30 second undo option like Gmail.