Friday, July 25, 2014

Summer Fun 2014 - Ice and Magnets

With warmer weather, and clear skies back, at least briefly, I decided to pull out one last ice project for the summer.  This time, I had frozen super strong, rare earth magnets into the ice cubes.  The magnets we used were very small, and would not be good for babies, toddlers, or preschoolers.  I also froze a few ice blocks with regular refrigerator magnets, but they were not strong enough to have any effect on each other through the ice.

My thinking was that the magnets inside the ice would stick the ice cubes together, or push them away from each other, depending on the poles of the magnets inside of them.

It worked too, but only where the magnets met, close to the surface of the ice.

The real fun came when we pulled out our wand magnet, and the girls discovered they could yank the little magnets right out of the ice by passing the wand, in the air, above the cubes.

Then, by placing the wand under the chair (our outdoor play table is still covered in a fortified rock village)...

...they could move the stack of newly freed magnets, using them to push around the ice cubes.

It wasn't exactly the play time I had imagined, but they had a great time with both the magnets and the melting ice, creating mazes, and then bulldozing their way through.

And, it got them back outside for a while.

Thursday, July 24, 2014

Summer Fun 2014 - Building a Da Vinci Style Arched Bridge

Sometime between 1485 and 1487, Leonardo Da Vinci, apparently sketched out designs for several "emergency" bridges.  They were intended for easy construction, using either pre-cut boards, or timber felled as needed, for a quick crossing of obstacles on a military campaign.

Building a model of a Da Vinci inspired bridge out of supplies found from around the house, might sound like a project for the school year, but I'm including it in our summer fun series, because the Da Vinci designs are so simple, building them is more like doing a jigsaw puzzle, than working out an engineering problem.  And, on a too-hot-and-stormy-to-go-outside kind of day, who doesn't like a good puzzle?

Most, if not all, of the Da Vinci bridge models you can buy come with notched planks - one notch right in the middle, and two an equal distance from either end, on the opposite side from the middle notch.

We started out using chopsticks without notches (the step by step building instructions we followed can be found in the resource list at the bottom of the page).  Actually, we started out using sugar cookie sticks...

...but they snapped under the pressure holding the bridge together, so we moved on to chopsticks.  They worked perfectly for small, simple bridges...

...but tended to roll, and come apart as additional levels of planks were added.

Notching the chopsticks seemed difficult, so we opted to cut notches in drinking straws... use in combination with the sticks.  This worked really well...

...making the building process so much easier, except that as more sticks, and straws were added, the pressure proved to be too much for the straws as well...

...and they started to bend in the same spots where our cookie sticks had broken.  If nothing else, the cookies, and straws served to highlight how the design uses gravity and friction to direct the pressure down, to hold the pieces in place.

Finally we read, that while most of the models come with notched planks, the original sketches actually called for the planks to be lashed together with rope.  I'm not sure if that is correct, because none of our other sources agreed with it, but we tried it anyway...

...tying the chopsticks in place, with short lengths of yarn.

Not only were we able to build the bridge longer, and higher...

...but it was sturdier - if still a little springy.

In fact, successfully testing our bridge with one book, we built on until we had a complete half circle, at which point friction, and gravity started working against, instead of for us.

The taller bridge easily held two semi-heavy, hard back books.  We tried a third book, but the springy bridge sprang back with enough force to knock the books off, and flip the bridge across the room - one of Newton's laws at work, I'm sure.

I can't imagine, that soldiers being flung bridge and all, into a river, would be very happy.  That of course, brought up the question of how you were suppose to get across the bridge, anyway.  My thinking is that Leonardo intended for cross planks to be added to the frame once it was in place, to allow soldiers to march right across.  But then, Barbie might have the right idea, and it might have been intended to work as a sort of arched ladder, more than a bridge.

At any rate, the one thing we did learn, was that in this case, as an architectural engineer, Leonardo Da Vinci was an excellent - artist.

Resources we found helpful:

Katerina Lipertova's Practical Science Activity created by TES Science - includes a video clip of students building various sized Da Vinci bridges, up to some large enough to stand on.

Instructions for Building Leonardo Da Vinci's Self-Supporting Bridge.

Leonardo Da Vinci Inventions from Pathfinder's Education Support - talks about the bridge being lashed together in Da Vinci's original design.

Log Bridges and More - a picture of a similar design, built life-sized, out of logs.

Leonardo's Freestanding Bridge from MJ2 Artisanos - for the idea of the straws.

Wednesday, July 23, 2014

Summer Fun 2014 - Odds and Ends

Thanks to all the fun Claire and her group have been having with a Leonardo Da Vinci study over at Angelic Scalliwags, we're now completely lost in a free standing bridge project.

While we tinker away with chopsticks and straws (sadly cookies aren't working), here are a few other fun projects, and games we've been playing with this summer, that just haven't been quite enough for a post on their own.  Like did you know you can spin homemade silly putty (two parts liquid starch to one part glue - Coffee Cups and Crayons, who inspired my 15 year to make a batch, used one part liquid starch to two parts glue) is a lot of fun to twirl up off the table with a chop stick? 

Or, that you can't really build an good Roman arch with Rice Krispie squares?

You can get it to stand for a while...

...especially if well braced...

...but in the end they are just too squishy while fresh, and too uneven when dry.

They do however work nicely for building more primitive projects, and when combined with the right book...

...can still be fun.

It is possible to balance a fork and spoon on a toothpick perched on the edge of a glass.

If you think that's amazing, check out the what Allison at All For The Boys managed to do with with two toothpicks, and an apple, instead of a glass.

Or, for a slightly less nerve fraying challenge, you might want to check out the "fine art" jigsaw puzzles, available for free online, at JigZone.  They've come in handy for us, over the past few weeks.

Click to Mix and Solve

As for me, well, I'd still like to build a Leonardo-type bridge out of sugar cookies...

...if only we didn't have another round of baker-banner heat forecast for today.  A little more tinkering, and a slightly crisper cookie, and it just might work.

It's great to be a homeschooler.

Linked with The Summer Linky Party: Week 6 at Apron Strings and Other Things.

Tuesday, July 22, 2014

Summer Fun 2014 - Hand Painted Post Cards

The girls were so inspired by Kandinsky and his "noisy paint box", the other day, that as soon as we had finished our cookies, they wanted to paint.  Wanting to keep it small, after the cookie project, I gave them note cards, with water color paints  - the first supplies I happened upon in our craft cupboard.

I figured they'd paint one, or two cards worth, and be done.  But, they were really inspired, and spent more than an hour, carefully painting dozens of cards. 

As I looked at them drying on the table, I wondered if we could put them to use as post cards.  I've seen people making their own post cards with note cards before, but ours were small, 3'' x 5'' cards, painted with water color paint.  I wasn't sure they'd make it through the mail.

The girls liked the idea though, so we decided to give it a try, with a test card to start.  C (age 8) picked one of the pictures for Grandma, signed it...

...glued an extra card to the back... make it sturdier...

...and brushed a quick coating of watered down glue, with smooth long strokes, to seal the paint (we hoped).

When that was dry, we flipped the card over, and drew a line down the middle, for a title and message on the left...

...and addresses and stamp on the right.

She popped it in the post, and we waited... see if it would make it safely to Grandma's house, or not.  Not only did it make it intact, but Grandma was so thrilled, she's already framed it to hang on her wall.

Email is wonderful, and incredibly convenient.  In fact, if it weren't for email, I wouldn't have had instant access to a picture of my mother holding C's painting, to show to her.  But, looking at the grin on C's face, when she saw her card in her grandmother's hands...well, there's something to be said for the personal touch of a hand painted post card.

Monday, July 21, 2014

Summer Fun 2014 - Root Beer Floats - Experimenting With Nucleation

We had both diet, and regular root beer left over from a buoyancy/density test, for a sink or float experiment, to meet the final requirement on our library's science themed summer reading list...

...and Sunday just happened to be National Ice Cream Day.  It only seemed fitting to set up a summer, Sunday science, snactivity with root beer floats for everyone - including a few neighborhood friends who came running, when I called my own inside. 

First we talked about nucleation - the process of the carbon dioxide bubbles getting stuck in the craggy, oxygen bubble covered surface of the ice cream, where they sit pulling in more, and more bubbles, becoming larger and larger, creating a frothy, delicious, fat coated foam.  Then, I turned the children loose to experiment.

We made some floats by:
  • dropping ice cream into the root beer,
  • pouring root beer over small scoops of ice cream,
  • pouring root beer onto ice cream, that had been pressed, and smoothed as much as possible into the bottom of the cup
  •  and pouring root beer onto melted ice cream - which made a wonderful root beer fizz.

We used vanilla ice cream and:
  • warm regular root beer,
  • cold regular root beer,
  • warm and cold diet root beer,
  • and cold Coke Zero...

...observing the levels and quality of foam, and being delighted to find ice crystals forming in the root beer left to sit on top of the ice cream.  Some of our soda sat for a while before we got around to adding ice cream, and just as you might imagine, the foam was nearly as flat as the soda.

Then, just to be sure we were observing a physical change and not a chemical one brought on by combining ice cream and soda, we added some root beer to plain milk.

That brought our experiments to an end, as we switched over to a discussion of Laverne and Shirley, and Laverne's love of milk and Pepsi, and how I always wondered what that would taste like.  

If it's anything like root beer and milk, I wouldn't recommend it.

Resources we found handy:

How an Ice cream Soda or Float Works from,
Kitchen Chemistry from,
Fizzics from The Fizz,
and Why is There So Much Foam in a Root Beer Float?  from Wonderopolis.