Experiments – Beijing Kids

To the Lab: Kitchen Science Experiments

Sat, 19 Oct 2013 04:51:00 +0000

Whether you kid loves science or loves making a mess, kitchen experiments are a great way to have fun and learn the basic prinicples of physics and chemistry. Here’s our top science-based activities for the home laboratory.

Fizzing balloon inflation
What You Need

A plastic bottle
A Balloon
Vinegar
Baking soda
Funnel (or a straw)

What to Do
Use a funnel (or failing that, a straw) to pour about two teaspoons of baking soda into an empty balloon. Stretch the opening over the neck of a plastic bottle containing two tablespoons of vinegar, being careful not to let any drop in. When you’re ready, hold the rubber tightly, let the powder drop in and watch as the balloon inflate before your eyes.

The Science
When baking soda (sodium bicarbonate) mixes with vinegar (acetic acid) mix together a chemical reaction occurs, releasing carbon dioxide in the process.

Jumping Raisins
What You Need

10+ raisins
Two big clear glasses
Clear carbonated drink (e.g. tonic water, Sprite etc.)
Water

What to Do
Half-fill one glass with water and the other with a clear carbonated drink like tonic water or lemonade. Ask your child whether they think raisins will float or sink when dropped into the liquids. Next, simply take two small handfuls of raisins, five or more in each hand, and drop them into each glass simultaneously. Observe the results. The raisins will initially sink but watch as the ones in the carbonated drink begin rising to the surface and falling again, giving them the appearance of jumping or dancing.

The Science
The raisins initially sank because they have a higher density than the liquids. But their surfaces are covered in dents which become air pockets when they are dropped in, attracting the carbon dioxide bubbles. With the bubbles attached, the raisin is now bigger but has virtually the same mass, meaning it is now less dense than the carbonated drink. This causes it to rise until it reaches the surface, the bubbles pop and the initially density returns.

Bubbling volcano
What You Need

850g plain flour
300g salt
Water (warm and cold) 4 tablespoons cooking oil
Drink bottle (1/2 liter)
Red food coloring
2 tablespoons baking soda
Vinegar
Washing up liquid

What to Do
Put the flour, salt and cooking oil in a bowl, adding approximately 500ml of cold water and mixing up with your hands to reach the desired consistency – smooth but not too watery or slippery. Place the empty plastic bottle on a baking tray and mould the mixture around the bottle to form the body of your volcano with the bottle’s opening emerging from the top.

Next, fill the bottle to near the top with warm water and add five drops of washing up liquid that will give your lava more bubbles. Next add your baking soda and a dash of red food coloring. Gently introduce the vinegar and watch as the volcano erupts with bubbling red lava.

The Science
Just as with the balloon experiment, this is all about the carbon dioxide released from the chemical reaction between vinegar and sodium bicarbonate.

Invisible Ink
What You Need

Lemon/lime
Paper
Small paint brush
A clothes iron

What to Do
Use a lemon squeezer (or just your hand) to extract the juice from the lemon or lime into a bowl. Dip the paintbrush in and begin drawing or writing with the invisible ink on the paper. Leave it do dry and then heat the paper with the iron and see your work appear as if by magic. Be careful not to hold the iron on for too long or you may burn the paper.

The Science
The acidity of the lemon weakens the paper. When exposed to heat, the acid burns and turns brown before the paper.

Pomodoro in Action: One Writer’s Attempt at Using a Popular Learning Technique

Nimo_Wanjau

I recently bought a Nikon D3200 and decided to actually read through the 212-page instruction manual. It’s not what I usually do, but given some of my past experiences I decided it is better not to overlook the manual this time. Thanks to the Pomodoro technique, the experience wasn’t that boring at all.

Several months ago, I bought two bookshelves from IKEA. The picture made them look so easy to put together that I offered to take the other one after my sister carefully followed the instructions to assemble hers. I thought I would take me less time if I just looked at her piece, but it turned out to be quite the opposite. I ended up confusing the boards and using the wrong screws a couple of times.

The camera I just bought is an entry-level SLR, but its operation mode is similar to the more advanced and professional ones, like my cousin’s pricy Nikon D800. I still couldn’t figure out why it was better than mine, despite playing around with it.

I managed to read the first 20 pages quickly and learned to put the camera together so it was ready to take photos. After the initial excitement, I almost repeated what I used to do: use common sense and wing it, until I happen to read about Pomodoro, a technique that helps people focus and a colleague recommended on the blog.

The technique gets students to break up intensive study periods into timed short periods between shorter units of rest. After a set of Pomodoros (four 25-minute periods of non-interruptive reading in between of three five-minute break), I was surprised to have read half the manual with camera in hand. I managed to explore functions that I would never have figured out through common sense.

Instead of setting everything on automatic, I was able (although not skillfully) to use various manual controls. Not at all a bad way to spend two hours that I would normally use to watch TV or play Plants vs. Zombies.

Unlike casual reading, setting a Pomodoro to study is like making a commitment. The rules is, no matter what happens, you deal with distractions later and continue your task. It is better to use at home than in the office because there are really few urgent tasks you need to do immediately. If you tell your family members in advance not to pop in during the timed periods, your experiment is more secure.

Make a commitment before you set the Pomodoro. Ask yourself if there is anything more important to do during this timed period. If not, there is no excuse to idle when the timer is running. You can also download the to-do sheet and task inventory sheet to better organize your time.

You can buy a cute-looking official Pomodoro tomato timer here or a knockoff on Taobao. I downloaded a Pomodoro app for Android (also available on Apple and iPad); when the timer is set, no other functions pop up. The app is free, so give it a try!

Photo: Wikimedia Commons

Need A Cheap Purifier? Here Is a Do-It-Yourself Version

Nimo_Wanjau — Tue, 23 Jul 2013 04:00:00 +0000

After staying in Beijing for nearly four years, I’ve learned to look for good bargains, so when I came across this do-it-yourself purifier post I could feel my sense of cheapness being called upon (despite the fact that the picture looks like a broken air conditioning unit).

The post on Tumblr by particlecounting, who just started blogging about a week ago, claims that you can make an effective indoor air purifier simply by taking a flat front motor run fan and strapping a HEPA filter (purchasable from Taobao for RMB 58) for a total of just RMB 166 (as opposed to the RMB 11,000 or so you’d pay for a high-end filter).

The author, a self-professed "nerd" who says he is a 2012-2013 Fulbright Scholar based in Beijing and a PhD student in cultural psychology at the University of Virginia, gives a step-by-step guide on how to make your own, accompanied by pictures.

In a subsequent post, the author also documents a series of tests he conducted to study the effectiveness of his DIY purifier. He conducted a particle count of the air inside the room before switching the purifier on and used the US Embassy’s AQI to correlate with his particle counter and tested the air for eight hours in his bedroom with the windows and doors closed. He also took into account variables like someone entering and leaving the room which might cause a gust of wind to blow into the room.

The author compares the effectiveness of the DIY with a state of the art purifier based on data collected by myhealthbeijing blogger and Beijing United Family Hospital Doctor Richard St. Cyr, who calculated his air quality reductions on the air outside as opposed to the inside air, which the author believes is a better approach (he later updated the post by noting Dr. Richard conducted his tests with the doors closed for one hour).

In the end he acknowledges that variables like room size (his room is 6.5m smaller than Dr Richard’s) make the comparisons imperfect but concludes that his DIY filter is "roughly comparable to an expensive filter at far lower cost."

Photo courtesy of farm7 via Flickr