Monday, June 12, 2017

Balloon Rocket Cars

I am always looking for an easy project I can do in a classroom of 30+ kids. If I can quickly put kits together, that's great, but many projects, especially when preparing for 30+ kits, take a lot of work and time. So, when I found a kit for this project for $1.20/kit, I jumped on it and bought 4 sets of 10 kits. But I realized that I could probably put a kit together cheaply with every day materials.
Putting the vehicle together took matter of minutes, which was great since I only had an hour for the project. Then they were asked to power it by attaching a balloon to it. They were given a choice of two different sized balloons as well as complete freedom to shape and attach the straws whichever way the students wanted to try. I like to tweak things a bit, forcing the students to figure things out on their own.
The students had a fantastic time trying out different weights, sizes, attachments and learned while having fun. Unfortunately, we didn't have enough time to try out the incline surfaces and frictional losses. But, I'm looking to continuing with it during next school year.
I hope you’ll have fun with this project!

SUPPLIES:

For Vehicle:
  • 1 Corrugated plastic or cardboard piece for the vehicle body (3 in x 5 in)
  • 2 Plastic coffee stirrers
  • 1 Plastic drinking straw, cut in two equal pieces
  • 4 Foam disks for the wheels (~ 2.5 in in diameter and 0.5 in thick), but if you can't find these, you can cut them out from the same corrugated cardboard
  • Tape
For Rocket Balloon Power:
  • 1 Plastic drinking straw
  • 1 Balloon any size, but I took balloons of various sizes to the classroom to show the students the difference in air-power (also, to show them that BIGGER isn't always BETTER)

INSTRUCTIONS:


  • I used a delivery cardboard box to cut out my vehicle chassis (3 inches x 5 inches).
I was able to cut out several fairly easily and quickly. But I'm not sure I'd be up for cutting out 30+ sets x up to 12 classrooms. So, I would probably buy the kits, if I could still find them for $1.20/kit.
  • Cut a drinking straw in half.
If you have a bendy straw, cut off the bendy part first. Then cut the rest of the straw into two equal pieces.
  • Tape the cut pieces of straw on to the both narrow sides of the vehicle chassis, centering it across the width.

  • Insert one end of the coffee stirrer into one of the foam disks.


  • Insert the coffee stirrer with a wheel attached already through the already taped drinking straw on the vehicle chassis.
  • Insert another wheel on the remaining end of the coffee stirrer.

  • Do the same for the other side.

  • Cut a drinking straw to your desired length.
If you have a bendy straw, you can decide what to do with the bendy part. Then cut the straw to the length you want. It's up to you to decide which length works for your design.
  • Insert a straw into a balloon.
  • Put a rubber band around the neck of the balloon over the straw.
DO NOT tie the rubber band too tight. It can collapse the straw, and it won't work well (I've learned from experience).


I decided to create two different designs to see if there's a difference in the distance the vehicle traveled.
  • The 1st balloon rocket design has a straight straw piece inserted in the balloon.
  • The 2nd balloon rocket design has a bendy straw piece inserted in the balloon.
The 1st balloon rocket design traveled farther with the vehicle than the 2nd.
NOTE: I tried 2nd balloon rocket design with the bendy part up and down, and both positions had problems. Why don't you try it and see what it does?
PROBLEM SOLVING:
  • As soon as the students started testing their balloon rocket cars, they complained about the wheels coming off completely or their cars curving to the right or the left. I challenged them to come up with a solution to their problem.
Many started with taping the ends of their axel to stop the wheels from coming off, but it didn't stop the wheels from wobbling and not going straight (which was one of the requirements of the project).
  • Some complained that their vehicles refused to move, even with a gigantic balloon attached to it.
They had taped the axel (the coffee stirrer) to the axel housing (cut drinking straw), and it couldn't rotate. Therefore, the wheels couldn't rotate, which prevented the vehicles from moving.
  • Some students did blow gigantic balloons and learned that BIGGER isn't always BETTER.
Though the vehicles started fast, but they turned upside-down or rolled to one side due to the balloon rocket being too powerful for the vehicle. We tried to weigh down the vehicle, but it didn't work very well.
ADDITIONAL PROJECT IDEA 1:
This is part 1 of the add-on project I didn't get to do with the class.
  • Measure how far a vehicle will travel on flat surface.

  • Ramp 1 - Measure how far the same vehicle will travel on this inclined surface.
The plastic tub is 6 inches high, and the ramp is 22 inches long.
  • Ramp 2 - Measure how far the same vehicle will travel on this inclined surface.
The plastic tub stack (2 tubs) are 12 inches high, and the ramp is 22 inches long. The steeper descent made the vehicle more unstable, and it crashed into the nearby wall.
ADDITIONAL PROJECT IDEA 2:
This is part 2 of the add-on project I didn't get to do with the class.
  • Measure how far a vehicle with travel on flat surface (see project idea 1).

  • Measure how far the same vehicle will travel on carpet.
NOTE: The car on the carpet will not travel as far as the car on the smooth surface. The difference in the distance traveled is the force lost due to friction.
SCIENCE BEHIND THIS PROJECT:
I love Newton's Second Law, because it's easy for people to understand.
Force = Mass x Acceleration.
I use this all the time when I do projects with students. Whether it's a kindergarten class or a sixth-grade class, I write F = ma on the whiteboard and explain the relationship between them.
On flat surface (1st diagram): F = ma = F (Balloon) - F (Ground friction)

  • The total of all the forces acting on our vehicle will result in acceleration.
  • How fast the vehicle will accelerate will depend on the size of the force acting on the vehicle.
  • When the air in the balloon is pushed out of the straw through the back, the balloon is pushed forward. When the balloon is pushed forward and is taped to the vehicle, the vehicle moves forward with the balloon.
Actually, F=ma is too simple. What it really means is that F = ma = F (Balloon) - F (Ground friction). But in most cases, we assume F (Ground friction/Resistance) = 0 on smooth surfaces because it's very, very small.
On a ramp (2nd diagram): F = ma = [F(Normal) - F(GravityY)] + [F(Balloon) + F(GravityX) - F(Ground friction)]

  • The total of all the forces acting on our vehicle will result in acceleration.
  • How fast the vehicle will accelerate will depend on the size of the force acting on the vehicle.
  • When the air in the balloon is pushed out of the straw through the back, the balloon is pushed forward. When the balloon is pushed forward and is taped to the vehicle, the vehicle moves forward with the balloon.
If the ramp is smooth, F (Ground friction) = 0, too. F (Ground friction) depends the smoothness of the surfaces, not the angle of inclination. And conveniently, [F(Normal) - F(GravityY)] = 0, because they are equal and opposite forces.
So, the long equation is shortened to F = ma = [F(Balloon) + F(GravityX)].
NOTE 1:
In kindergarten, I use addition/subtraction to get them to understand the relationship between the three. If F is constant, and m is big, a is little and vice versa.
NOTE 2:
If you want to solve for F(GravityX), the mathematical equation is
F(GravityX) = F(Gravity) x sine(angle).
If you want to solve for F(GravityY), the mathematical equation is
F(GravityY) = F(Gravity) x cosine(angle).
NOTE 3:
In More Air-Powered 2, Frictional Forces, F(Ground Friction) is not 0.
The car on the carpet will not travel as far as the car on the smooth surface.
The difference in the distance traveled is the force lost due to friction.

Thursday, May 26, 2016

Duolingo.com

I love this app!

I don't usually download apps on my phone, but this is the one I use every day. I took four years of Spanish in high school, but since then, I've done nothing with it. I can read OK (sort of like speaking in broken Spanish. I try to make sense of it, mostly guessing at the vast number of words I don't know or don't remember). But since my husband introduced me to this app a couple of months ago, I can't put it down. 

It's an app that teaches you a foreign language.



It offers courses in a variety of languages (fifteen), mostly European languages, and there are twelve more languages in the works.


Select the language you want to learn, and you're on your way.


It starts with very basic skill and then go on to more advanced skills.


I'm at level 11 in Spanish, but at level 1 in Russian and Irish. I thought about doing all three languages at the same time, but I found that I got quite confused and couldn't retain as many words. So, I decided to concentrate on one language at a time.


This screen shot is about a translation questions, but there are vocabulary questions (writing the meaning down as well as pairing exercises), along with enunciation questions.


I do Duolingo on my phone, so I don't have access to this Spanish words learned list (at least I haven't found it on my phone), but I don't think this feature matters much. You can finish a lesson in less than five minutes, repeating a few select words and sentences at a time. I found this very effective.

My son and daughter have picked up on duolingo (both choosing German), and they like it. My son says Duolingo is better than Rosetta Stone (which my husband and I purchased for them to learn another language). 

So, if you have five or ten minutes to kill, this might be a good way to spend your time.

Monday, May 23, 2016

Bridge Building Series - Truss Bridge 2

Truss Bridge 2 – Straws & tape (A challenge project)

This project needs more accurate taping, which might be a tad difficult for primary students. However, I've done this project with a group of 3rd graders, and they were able to build sufficient truss bridges.

Supplies:
·         A bag/box of straws
·         Tape
·         Scissors
·         Small cups
·         Paper clips
·         Weights – pennies, paper clips, etc. Anything is OK as long as they weigh the same. You want to compare how much different bridge designs can support
    
Instructions:
1.      Cut a bundle of straws to same size (~2 1/2 inches long). Leave some for different lengths. These will be cut to size.
2.      Tape four pieces together to make a square. Tape uniformly across all places. Create enough square to span an opening that is 10 inches wide.


Created bottom of the truss bridge first, then continued to build the sides of the bridge. (These squares measure to 11 inches in length.)



3.      After creating several squares, put cross bracings diagonally (cut these to size).


4.      Put the top pieces last and enclose the truss bridge.
5.      Place the truss bridge between two desks, tables, chairs, etc.


6.      Hang a small cup in the middle of the bridge (use hole puncher and paper clips) and load it with pennies, paper clips, etc. to weigh it down and test its strength.
Same amount as beam bridge

Added more coins
Added another bucket full of coins.
7.      Different size straws, too much tape on one side vs. the other side, etc. will create imbalance and weaknesses in the bridge structure. Try to balance taping, straw usage, etc. on all sides.


This straw and tape truss bridge was much stronger than I expected. I think I could have added another bucket of coins, but I ran out of bridge space. Maybe you can build a longer bridge and test how many buckets of coins your bridge will hold. Of course, the longer the bridge span, weaker the bridge. So, you might have to consider the bridge span vs. support strength of the abutment.

Remember, Engineering is all about failing and trying, again. So, try and try, again.

Friday, May 20, 2016

Tech Challenge 2016 Recap 3 (Test Trial Pix)

In this Tech Challenge 2016 recap series, we'll be following a group of fourth graders who entered the tech challenge for the first time.

One of the most important things to do when participating in the tech challenge is to attend at least one test trial at the Tech Museum of Innovation in San Jose, California. This 4th-grade team has attended  3 test trials this year. 

Here are some pictures of our 4th-grade team at the test trials they've attended in the Tech Challenge 2016 competition.

1st Test Trial
1st Test Trial
2nd Test Trial
2nd Test Trial
3rd Test Trial
3rd Test Trial
At each test trial, the teams initially test their proof-of-concept and then go on to test and improve their prototypes until the competition day. It also provides an occasion for the judges to check if the teams meet the technical requirements of the tech challenge. The more you attend, the more data a team has to improve its designs and eliminate the design and performance issues.

Maybe we'll see you next year.






Wednesday, May 18, 2016

Bridge Building Series - Truss Bridge 1

Truss bridge building instructions 1

We’ll make different truss bridges using two different materials - foam cubes and cut drinking straw pieces.

Design Rules for both bridges:

1.      Bridge must span 10 inches (25 cm)
2.      Bridge must have a place to attach a small cup in the center of the span (preferred).
3.      The ends of the bridge are not taped onto the support structure.

Bridge 1 – Marshmallow/foam cubes/cheese balls & toothpicks

NOTE: The best material for this project is foam cubes. However, a container of foam cubes can get very expensive (I've paid $27.49 for a container of 105 foam cubes), so if you can find more affordable ones, please let me know.

I've done this project with marshmallows, and it's doable (for intermediate grades). And cheese balls get messy, but doable as well.

Supplies:
·         A bag of marshmallows, foam cubes, or cheese balls
·         A box of toothpicks
·         Tape
·         Small cups
·         Paper clips
·         Weights – pennies, paper clips, etc. Anything is OK as long as they weigh the same. You want to compare how much different bridge designs can support
    
Instructions:
1.   Create a square with four foam cube pieces and toothpicks. Create 3 more. Put them together to create a cube. 


2.   Create several more cubes and put them together until you reach 10 inches in length. Remember, your bridge must be longer than the span it needs to bridge (add an inch or two to the total length of your bridge).
  

3.   Place the bridge between two desks, tables, chairs, etc.
4.   Hang a small cup in the middle of the bridge (use hole puncher and paper clips) and load it with pennies, paper clips, etc. to weigh it down and test its strength.

~same number of coins in the cup as the beam bridge project

added another cup of coins

added more coins to each cup

Again, this project works best with these foam cubes. I purchased from Amazon, but they are pricey. I did find some smaller foam cubes from the Dollar Tree store, and they worked well. But it's very difficult to find them consistently. You can see them on their online store, and the store managers don't seem to know when or if they'll ever get another shipment. So, if you find another source of reasonably priced foam cubes, please let me know.