Brushbots After School

We have a great after school program at my children's elementary school.  People from around the community come in to teach different subjects including:  jewelry making, cooking, gardening, karate, skateboarding, soccer, basketball, tennis, running, sewing, fashion design, legos, etc.  You name it, and there is probably a class for it.  I decided to offer a class in building brush bots for fourth and fifth graders.  The fourth graders learn about circuits in class and build a simple circuit using aluminum foil, a battery and a small light bulb.  Building on this, I decided to offer them a chance to build their own brushbots.

A brushbot is a circuit with a vibrating motor on top of a brush such as a nailbrush or toothbrush.

The kits are a bit pricey ($15-20), so I decided to make my own using a nailbrush, a battery holder, a switch, and a motor.  I had the motors from another project but had gotten them for about $1.00 each, the battery holder was $2.00, the nailbrush, $1.00 from Target and the switch was $3.50 at Radioshack.  So the total cost for my brushbot was $7.50.  It could have been cheaper if I had bought the components in bulk from internet supply stores, but I had only 4 kids in the class, so Radioshack was convenient.

Above are three of the bots built by the fourth and fifth graders.  They had a great time building them and felt a real sense of accomplishment when we got them all up and running.

Here is another photo.  The main problem we had was getting the kids to make a good connection to the various components with the wires and then taping them with electrical tape.  For some of the kids, it was a bit challenging.  But, after a few tries, most of them got pretty adept at wiring.  The other problem we ran into was balancing the bots so they vibrated without falling over.  That task involved moving the components around on top of the brushes until we got them balanced.  I used balanced motors, so to get the motors unbalanced to allow them to vibrate we attached alligator clips.  Today, the kids will finish making there vibrating bugs.  I will show photos of those next week.

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Models and Learning by Doing or How Design Failures Can Teach the Best Lessons

Today, I and a couple of volunteers went into the 2nd grade classroom and had the students build models of satellites.   The students have already had "changes of state" lessons in which they learn about solids, liquids and gasses.  Building off of that, I use the activity from teachengineering called Beat the Heat.
In this activity, I talk to the students about models.  We talk about how you can build a model car out of legos, or build a model airplane.  It is not the same as the real thing, but that you can build and test aspects of the design.  Today, we used plastic eggs as a model for the shell of a satellite that we want to send to Venus.  Venus is a hot planet reaching temperatures of 1,300 degrees Fahrenheit.  We talk about what kinds of things you would want to learn about Venus, so we decide a camera is one of the most important things you would want in your satellite.  Instead of using a camera in our test, we use butter.  The idea is to give the students a pat of butter and have them protect it from heat.  We also give the students various materials to use such as tooth picks, cloth, packing peanuts, cotton balls, balsa wood.

The students then design and build their satellite model using these materials.  

Next, they draw and label their designs.

Finally, I use box fitted it with a hole for a hair dryer for a heat source, with a thermometer and a viewing window with egg cartons in the bottom for holding eggs.  I then turn on the hair dryer and heat the box to 160 degrees F.   This is our Venus simulator or testing rig.

After the temperature in the box reaches 160 degrees F, we take apart the eggs and look at the results.

We learn that if the butter is kept away from the surface of the eggs, it generally survives, but if it is in contact with the egg, it will melt.

In the second of the six classes I ran this exercise with today I had one group whose butter completely melted.  The group was pretty dejected, but one of the other students spoke up and said,

" Don't worry.  Ms. Skalak told me last year that failing was a learning experience.  Last year when we built water filters I ended up with sand all in my water.  But, now I know better how to design the filter."

I asked the student if he remembered it more because it didn't work out as he had hoped, and he said yes.

Learning by doing is a great way to get the students to learn a concept not just with their head, but with their whole being.  I think this student learned many lessons last year:

•  he will never put sand in a water filter without something to hold the sand in the filter such as cloth or screen
• the failure of his design was a bit painful at the time, but it is something that engineers have happen all the time
• it is okay to fail, because it gives you an opportunity to learn and make it better

Are the students going to run out and build a satellite for NASA based on these ideas?  Of course not, but if they can learn something like this student did about failure, and the opportunity to learn something from the failure.   I think the exercise is more than worth it in time and effort, and besides, it is just fun to do.

Building an Egg Racer and an Interest in Engineering

I teach an after school class at our local school which the people who run it call "Eggineering".  In this class, well, I call it a class, but really it is an after school program that extends learning without being too school-like.  I have 5 one hour session in which I have fourth and fifth graders build a car I call an Egg Racer.  This idea was taken from another school which has all of their fifth graders build the car.

I don't have any photographs today, but will take some next week, but I thought I would share the initial write-up and the lesson on engineering drawing.

Last year I spent an hour working with the students on the engineering design process, but had a difficult time getting them to follow the process.  So this year, I decided I would concentrate on teaching them to draw their ideas, and the requirements, and then just let them go build.

Here is the writeup.

Eggineering:  Designing an Egg Racer

Team Members:         _________________________________

                                    _________________________________

                                    _________________________________

                                    _________________________________

Design Brief:  Your team has been assigned to design and build a fast, convertible sports car.  This car should allow a driver, an uncooked egg, to “drive” down a track going down the track and across the floor as far as possible.  In addition, the driver must survive a crash test on 6 foot track, crashing into a barrier.

Design Requirements: 

·      You will use parts from given design kit.

·      Car must not be wider than 12 ½ cm, including wheels and axles.

·      The car must not be longer than 24 cm.

·      The car must be open topped ( nothing above the egg’s head).

·      The total weight of the car and egg must be less than 10 ounces.

·      The car must include at least one of the following safety devices: seat belt, air bag, and/or rollbar/cage.

·      The egg’s face (a circle one inch in diameter – use a quarter) must not be covered so he can see the road. 

·      The egg may wear a safety helmet.

·      The egg must be able to get out of the car easily so he can be inspected for injury after the crash test.

Design Criteria:  Your team’s car will be judged on the following items:

·      Operation of the car, how far it moves down the track and how well it protects its passenger

·      Elegance of design and your engineering drawing

·      Use of available resources

·      Reliability (how consistently your car performs)

·      Ease of use (how easily your egg can be put in and taken out of the car)

Eggineering:  Designing an Egg Racer

Evaluation Guidelines

Judgment Criteria	Maximum Points	Score
Track Performance (1 point for each foot of travel beyond the track)	15
Crash Test Performance (10: no cracks; 5: minor cracks; 1 major cracks; 0: completely smashed)	10
Repeatability of Car Performance (how far car repeats distance performance on each of 3 trials) (5: excellent; 3: average; 1: poor)	5
Ease of use (can you easily get your egg in and out of the car) (5: excellent; 3: average; 1: poor)	5
Creativity:  How innovative is your car design, is it a Maserati or a Kia? (5: excellent; 3: average; 1: poor)	5
Did it meet design requirements:  (5: excellent; 3: average; 1: poor)	5
How good is your engineering drawing? (5: excellent; 3: average; 1: poor)	5
Total Score:	50

Materials:

·      Pipe cleaners: 2

·      Straws: 1

·      Craft sticks: 3

·      Cardboard

·      Wheels: 4

·      Axles: 2

Tools:

·      Glue gun with teacher’s assistance

·      Tape

·      Scissors

·      Rulers

·      Scale

·      Glue