Build a Rubber Band Powered Racecar

We just posted a new activity guide! Follow the steps to create a rubber band powered LEGO car! We used the NXT kits to build ours, but if you have some LEGOs with wheels and axels you should be able to modify our designs easily to start racing your cars. Remember, using your imagination and engineering skills is the name of the game. Race against your friends and try for the farthest distance for fastest car.

As you come up with new designs post comments and design tips.

Check out the new activity guide on the resources page, or download it directly.

Robot Olympics!

We’re busy creating another exciting activity guide; right now it’s in the “preliminary draft” stage now, but I wanted to give you a sneak peak at what’s to come. The Robot Olympics is a fun, math centric activity guide in which kids can build LEGO robotics and compete to build the best performing design.

Here’s a list of the events we’ve come up with, of course we’d love to hear your input as well.

1. Trace the Race Course – Build a car that can measure the perimeter of a complex shaped off-road race course by calculating the speed of a line-following robot.


2. Wheel Circumference - Measure the diameter of the car’s wheel and calculate the circumference. Then calculate the circumference by measuring the distance it travels and the number of wheel rotations. Discuss the accuracy of each method.


3. Slowest Car – Build the slowest car using different gearing ratios, and wheels.


4. Soccer Bot - Build a robot capable of “kicking” a ball into a goal.


5. Spy Olympics: Crack the Code - Figure out other groups’ Secret Number using graphing, probability and averages


6. Olympic Rope Climbing - Build a car that can climb a rope by reeling itself up a piece of string.


7. Steep Ramp - Build a robot that climbs the steepest ramp.
   Fast Car Race – Use gearing ratios and different wheels to build the car that can go the fastest!


8. OLYMPICS! – A final Olympics Competition that includes four different competitions: a Tug of war Contest, a Contest to build a car the travels a very specific distance, a Robot that can throw a ball into a basket, and an off road race.

Here’s one of my favorites, the Soccer Bot:

Goal:

To build a robot capable of “kicking” one of the colored plastic balls into a goal. Then calculate its probability of making the goal at different distances.

Main Themes:

• Probability and percentage
  
• Robotic aim and accuracy

Math Theory:
Probability is the chance that an event will occur in the future, based on past behaviors. The probability of your soccer bot making the next shot is the number of goals your robot has already made out of the total shots it has taken.
Probability = # of goals / total shots

Percentage is the ratio of goals made to the total shots attempted, expressed in the hundredths.
Percentage = (# of goals / total shots) x 100
Percents are shown with a percentage symbol at the end, for example 100% or 78%.

Activity Instructions:
Pre-activity setup:

• Construct a soccer goal that is about a foot wide. 
  
• It can be made out of cardboard, stacked books, or other construction material. 
  

Day 1

• Build a soccer robot to kick the ball towards a goal. Robots can also throw the ball, hit it like a billiards cue, etc.
  
• Test to make sure it can at least sometimes make the goal at both 3 feet and 10 feet away. 
  

Day 2

• If needed, iterate on the soccer bot design to make the ball go far enough to reach the goal from 10 feet away. 
  
• Test the soccer bot by taking 10 shots at the goal from 3 feet away. 
  
• Record the number of shots successfully made
  
• Calculate the probability of making a future shot from that distance. Represent this as a fraction, and then as a percentage. 
  
• Test the soccer bot by taking 10 shots at the same goal, but this time from 10 feet away.
  
• Record the number of shots successfully made, and calculate the probability of making a future shot from that distance. Represent this as a fraction, and then as a percentage.

Construction Tips:

• Build a solid, sturdy robot! Repeated kicks of the ball will rattle it apart if it’s not strong enough.
  
• There are many styles of ball hitting to mimic, here are just a few:
  
• Kicking with a vertical “leg”, similar to a human kicking or a pendulum swinging.
• Hitting the ball sideways, like pinball flippers
  
• Hitting the ball straight on, like a billiard/pool cue
  
• Throw the ball, as a human (or catapult) would
  
• Either a motor powered kicker or a spring loaded system can be used.

Discussion Questions:

• Did your robot have a higher probability of making the goal at 3 feet or 10 feet? Why? How much of a difference was there?
• How far away do you think the goal would have to be to have a less than 1% probability of making each shot?
  
• What types of robots had the highest probabilities of making each shot?

Activity Variations (optional):

• Iterate the design to make a better robot that has a higher probability of making the goal. This could be easily run as multi-round competition over 3 or more sessions where the students iterate (and document design changes!), improving their robot each session.
• Write journal entries and/or draw diagrams of your initial design, what you changed and why, and your final design.

Resources:
International annual robotic soccer competition: http://www.robocup.org/