Wednesday, May 16, 2018

Monday, May 14, 2018

Science of Cleaning

Chemistry is so interesting.

I've been reading about the cleaning powers of baking soda, and I wanted to do this experiment one day. And that day is today.

Quotes to reglaze a small shower stall came in between $1,500 - $2,500, and I wondered how clean can I get this shower stall on my own?

I watched some videos on Youtube and spent less than $20 on cleaning supplies from Target and Dollar Store.

I used Sharpies to write down what I used to make up the solutions on the bottles.

This is what I'm cleaning today.

The cleaning recipes I've tried:
  1. Spray white vinegar on the surface. Left it for 30 minutes. Scrubbed it with a soft brillo pad. No noticeable improvement.
  2. Baking Soda mixed with water. Covered the surface and left it for 30 minutes. Scrubbed it with a soft brillo pad. No noticeable improvement.
  3. Mixture of Dawn dish washing detergent and white vinegar. Left it for 30 minutes and an hour. Scrubbed it with a soft brillo pad. No noticeable improvement.
  4. Easy-Off Oven cleaner sprayed on the surface and left it for an hour. Scrubbed it with sponge. Scrubbed it with a soft brillo pad. No noticeable improvement.
  5. Baking Soda mixed with a little bit of Clorox to make it into a crumbly paste. Covered the surface with it and left it for an hour. Scrubbed with a soft brillo pad and voila! See below for results.

I scrubbed the shower pan twice. I missed some areas after the 1st time, and I tried it again. And it got cleaner!

When I was using Clorox, I had the window and the door open with a fan going. I also had a mask on and wore dish washing gloves. It really wasn't too bad, but I was taking precautions. If you do want to try this at home, please ventilate the area sufficiently.

Science behind this cleaning-

Baking soda, sodium bicarbonate, belongs to the salt family, and if you try it, it’ll taste like salt (but not as salty). Sodium bicarbonate, NaHCO3, is a mixture of carbon, sodium, hydrogen and oxygen. Baking Soda is slightly basic, and it is the key to being a good cleaning agent.
The active ingredient in Clorox is sodium hypochlorite, NaClO. It bleaches, removes stains and disinfects. Other ingredients in Clorox include sodium carbonate (washing soda). It breaks down alcohol and grease stains. And Sodium hydroxide (lye) breaks down fatty, oily or acidic stains.

No wonder it cleaned so well!

For more information on Chemistry of Baking Soda and Clorox, please check out the links below.

Thursday, May 10, 2018

Catapult Hack-a-thon!

This is a project I picked up from RAFT in San Jose. This would have been a good project on its own, but I wanted to challenge my 6th graders. So, for the first ten minutes, I have the students quickly put this kit together. Then we spent the rest of the class period hacking it for distance and accuracy.

This is what the students built in the beginning.

Supplies List:
  • 1 binder side or a cardboard the size of a binder 
  • 7 unsharpened pencils
  • 2 binder clips
  • 1 soft pompom ball
  • 1 plastic spoon
  • 1 rubber band
  • 1 pencil top eraser
  • 5 rubber tubes with a hole in the middle
  • 1 rubber tube
Build Instructions:
As I said, I built the catapult then left as an example for the students to see and build. I also leave out the instruction pamphlet for them.

Once they build the catapult, they come up to the line and shoot it to see how it flies. Then the students are instructed to "hack" the catapult. The students are encouraged to do anything they want to it, except they can't cut the rubber tubes and break the pencils.

And these are what the students came up with (I didn't add all 4 classes of modifications).

The best of the best! (see below)
This design was so awesome that this design gave me goosebumps!

1st hack attempt. This didn't shoot as far as the team had hoped.

The final hack!
Closed. At rest position.

Fully armed.
Ready for a shot.
Fun group photos:

Tuesday, May 8, 2018

LEGO rack and pinion gears 2 - Mechanisms

Some of my favorite gears to play with in LEGO is rack and pinion gears. I guess I like watching the gears move from side to side.

This is what we're building today.

The pieces I'm going to use today:

I didn't have the pieces the book used, so I tried to use replacement pieces.
Pictured above are red and yellow flat pieces for the rack and pinion gears, 
but they didn't work out at the end. So, later on, 
you'll see orange pieces to make this mechanism work. 

Pictured here is size 5 gray stick piece. What you need is size 3 gray stick piece.

I thought I might have fun with a mini figure since my daughter enjoys collecting them so much.

These are the replacement pieces for the red and yellow piece pictured in the first photo.

The red and yellow pieces are pictured in the background.

Thursday, April 19, 2018

The Tech Challenge is Coming.

This is a program I DEARLY LOVE. 

I've been an adviser since 2013. But after five years of being an adviser, sometimes two teams, I'm taking a break this year. 

I had hope to participate as a volunteer, but a sudden change of events prevented me from doing so. Still, I hope to attend the Showcase next week.

As I noted on my Cal Day 2018 blog, I haven't been able to attend Cal Day, because I was fielding teams in the Tech Challenge. So, if driving to UC Berkeley is too far for you (or taking BART), then you have something else to consider this weekend. Attending the last weekend of test trials at the Tech Challenge!

I know. It's going to be crazy. 

People are going to be EVERYWHERE. But you can't get any closer to the action than this. Especially, if you have small children who are interested in Science/Engineering and would like to see things go and do interesting things, this is the place for you. 

And it's FREE.

Have a great time!

My previous Tech Challenge 2018 post with more pictures.

PS - You might be able to get into the Museum at a discount, too.