Monday, December 23, 2013

Friday, December 20, 2013

The Shape of a Tree

When the last leaf has blown away and the trees are left bare - that's when you can see the true shape of a tree. Each kind of tree has its own shape and pattern of branching. Some have branches that alternate up the trunk, like oaks. Others have branches that come off the trunk in pairs - "opposite" branches. That's what maples do. Some trees have weepy droopy branches, like the willows. And others, like Staghorn sumac, are tipped with fruit clusters that the birds love to eat in the winter.

The shape of the tree is its "skeleton", with the trunk and branches making up its bones. Some of those bones are white, some are dark. Some are smooth, some rough.

Grab your sketchbook or journal and go on a tree skeleton hike. Draw the structures of your neighborhood trees - and maybe do a rubbing of the bark. It's a good way to get to know the trees without their leaves on.

Today is STEM Friday - head over to the STEM Friday blog to see what other people are talking about in science, technology, engineering and math.

Friday, December 13, 2013

Some Things Float ~ Some Things Don't

Things That Float and Things That Don't
by David Adler; illus. by Anna Raff
32 pages; ages 5 - 9
Holiday House, 2013

Last week we were testing how well glitter fell through water, and it got me thinking about all the "bathtub science" my kids used to do. You know: toss an apple into a bathtub full of water and it bobs on the surface. But toss in a quarter and it sinks - which makes anyone sitting in the bathtub wonder: how can a huge ship float if it's made of metal?

It's not just the material of an object - or its size - that determines "floatability". Shape has something to do with it as well, and Adler shows how.

Take a piece of aluminum foil. If you put it on top of water, it will float. It will float even if you crumple it a bit into a loose ball. But if you smoosh it into a tight ball it sinks. So it's not weight that matters - because it's the same amount of foil. It's how much space it takes up - its density. Adler explains density, and demonstrates why even "heavy" clay boats can float. He shows what displacement is all about and offers lots of opportunities for kids - and parents - to ask questions and test household objects. All you need is a bathtub. Or a dish pan or a wading pool or a large mixing bowl...

Today's review is part of the STEM Friday blog. Check out the other science books and resources reviewed this week. Review copy provided by the publisher.

Monday, December 9, 2013

Anyone can Learn some Computer Code...

This week - December 9 through 13 - is Computer Science Education Week. It's also a great week to celebrate Grace Hopper, an American pioneer in computer science.

What better way to celebrate than to learn how to write computer code? If you've never written any code before, don't worry. The folks at the Hour of Code site have some videos and puzzles to get you started. All you've got to do is click on the GO button in the "write your first computer program" button.

And it's FUN! There are puzzles with angry birds and zombies ...and lots of opportunities to run into walls or flesh-eating plants. These are great puzzles to get your brain thinking about logic (if ___, then ___) and spatial orientation (how many spaces/ turn right or left?)

Go. Have fun. Play with computer code for an hour... even if you think you'll never use it again.

Friday, December 6, 2013

Snow Globe Science

photo by Sophia at Mamasaymamaso
I've got a snow globe that I love - and a magic wand full of glitter and tiny stars and moons. And one of the questions that I've been mulling over is: how do they get that glittery stuff to float so gently (instead of fall down fast)?

So I thought it might be fun to explore how things fall in liquid by experimenting with glitter globes - simple globes you can make at your dining room table.

What you need:
  • a small glass jar with a tight lid (large baby food jar works well)
  • 1 or more skinny jars for liquid testing (like spice jars)
  • water
  • mineral oil
  • glycerin
  • glitter (different kinds if you can find them)
  • small plastic figures (old holiday ornaments work well)
  • hot glue gun
  • toothpick & dish soap
  • pipe thread tape (to help seal jar lid if it leaks)
  • measuring spoons
  • optional: stopwatch for timing how fast glitter falls

How fast does glitter fall through different liquids?  
Fill your liquid-testing jar with water fill a  1/2 teaspoon with glitter. Before you add glitter to the water, dip a toothpick into some dish soap and touch it to the surface of the water. This will break the surface tension so the glitter won't glom all together on top. Then add the glitter and start timing.
Do the same thing with a testing jar filled with mineral oil.
Then try different mixes of water and mineral oil.
Try adding small amounts of glycerin (1/4 teaspoon at a time) to see whether that changes how fast your glitter falls.

Do some kinds of glitter fall faster than others?
Test different kinds of glitter with water to see how fast they fall. Use the same amount (1/2 teaspoon) for each type of glitter. Remember to use a toothpick dipped in dish soap to break the surface tension before you add the glitter.

Make a snow globe!
Glue a figure onto the lid of your baby food jar. When it's dry, add the liquid mix you like best, then add your glitter (remember the toothpick/dish soap trick). Put some pipe thread tape around the inside of the jar lid and screw it on. Now shake and enjoy.

 Today is STEM Friday - head over to the STEM Friday blog to see what other people are talking about in science.