Liquid nitrogen ice cream

For the potluck on the last day of school, I made ice cream using liquid nitrogen.  Basic recipe: milk, cream, sugar.  For strawberry ice cream I added vanilla plus strawberry puree, and for ginger ice cream I added ginger syrup and ginger bits.  The LN2 cools it down real fast.  It was a big hit.

Astrobiology projects

Yesterday Vera visited the elementary to help provide feedback on the students' completed astrobiology projects.  Each student made a poster, and made a short presentation using his/her poster as a prop.  The project was to imagine an ecosystem on another world, combining what they have learned about ecology all year (primary producers, primary consumers, etc) with what they have learned about other worlds in the last few weeks.  This was the last physical science session of the year.  Thanks to all the kids, parents, and teachers for a great year!

Planets, planets, planets

Last Friday Vera visited primaria.  The kids who stay for afternoon care had been learning about planets and stars there, and on my last visit I could see they were really excited about it.  For example, at snack time I was showing them pictures of Darth Crater on my phone:

(This is Mimas, a moon of Saturn; the crater's name is not actually Darth Crater but it's a good joke for kids.)

So, although generally we prefer hands-on activities rather than powerpoint, I thought this was one case where a slide show kind of presentation was appropriate.  So Vera gave a highly interactive tour of the solar system slide show, to two groups of 10-11 each.  The kids were super excited and tired her out!

One way to extend this in the future would be to have kids draw pictures of what they imagine other planets to be like, before and/or after the slide show, and see what their preconceptions are as well as how their conceptions changed.

A better way for kids to build circuits

I just learned about this from a fellow astronomer and part-time kid science instructor: squishy circuits.  It's worth watching the 4-minute video.  Next year, this is definitely the technology I'll use to get little hands to build circuits without frustration!

Astrobiology 101

On Wednesday Vera visited the elementary to kick off the astrobiology
unit and projects.  The idea is that the students have been studying
ecology on Earth all year, so here is a chance to put their
understanding to work in other environments.

Vera and I discussed how to kick this off: with a lecture with
pictures, a hands-on activity, what?  We concluded that it was best to
make it a conversation.  She went in with some questions designed to
elicit what they know and what they don't know about extraterrestrial
environments.  Depending on their responses the conversation could go
just about anywhere, BUT the plan was to stop and write down the more
complicated questions that came up, and use that as a list of possible
project topics.  For example, there might be a short discussion of the
various kinds of exoplanets which have been discovered, but if someone
asked, "But how do scientists discover exoplanets?" then she would add
that to the list of potential project topics rather than starting such
an open-ended new discussion.

Vera reports that it went very well.  She was surprised at how much
the kids knew, especially the younger kids.  But more important than
what they already knew is how curious they were, and how willing to
put together different pieces of their knowledge to come up with new
ideas.  In the nest two weeks, they will pursue projects guided by
Lorie, and then Vera will return in a sort of capstone session.

Siphon Tank

The school year is coming to an end and I never got time to do an activity based on this idea, so here is a quick video.

Focus, kids!

The Primaria kids are learning about solar ovens; they fried an egg
yesterday and they baked cookies today.  I brought in a neat piece of
equipment to complement that: a parabolic mirror about 24" in
diameter.  If you point it at the Sun and put anything flammable at
the focus, it will burst into flame in about one second.

I also brought a larger flat mirror and started by having the kids try
to figure out how to set a piece of paper on fire.  (I knew they
wouldn't actually be able to do it without guidance, so there were no
safety issues at this stage.)  After watching what they did, we
discussed some very basic physics:

--you can't have too many people crowding around the mirror, just as you
  wouldn't put the mirror under a tree

--you want to point the mirror at the Sun

So I pointed the larger flat mirror at the Sun and had them try again.
When they couldn't, I pointed out how the "small" mirror was curved
and explained why that was important: light hitting the edge of the
mirror will be bounced toward a point above the center, and light
hitting the center will also be be bounced toward a point above the
center.  All the light meets at one point! 

With that in mind, I had the kids form a line and I helped them ignite
paper one by one for safety reasons (most of them were also too scared
to try by themselves).  I showed how putting the paper directly on the
mirror was no different than just putting the paper in regular
sunlight. As we lifted the paper above the surface of the mirror we
could see the light start to focus down on a smaller area of the
paper.  At just the right distance from the mirror, all the light is
focused on such a small area of the paper that it starts to smoke!

This one-by-one part of the activity took most of the time.  There was
little or no time for many of the add-ons I had imagined, such as
connecting with the idea of a magnifying glass, discussing how to
store solar energy so you can use it at night, relating to the
temperatures of different planets (concentrating the light mimics the
effect of being closer to the Sun), and having them draw how it works.
With some of the groups, I had brief discussions of some of these
ideas, but we definitely could have used more than the allotted 20
minutes.  I especially wish we could have done the drawings...it would
be really interesting to see what the kids would come up with.

I wore pretty dark sunglasses for this activity.  At one point I took
my sunglasses off to lend them to a child, and I was just about
blinded...I did have a blind spot for about 5 minutes afterward.  So I
would recommend bringing sunglasses for the kids too.

You don't necessarily need a mirror as large as the one I was able to borrow.  I've seen survival shows where people used parabolic mirrors as small as the ones in flashlights to start fires.  It just requires more patience, and more fine motor skills to hit that small focus.

If you want to add a little more physics, note that the Sun provides over one kilowatt per square meter (the "solar constant" is 1.361 kW/m2, but the atmosphere takes a bit of that).  Kids in the upper elementary grades should be able to figure out how many watts their mirror collects and compare that with the power of their microwave oven, the energy consumption of a typical house, etc.