How Many Numbers Can You Remember?



Are you good at remembering addresses and phone numbers? How many numbers do you think you can remember? Try this experiment to test your digit span, the maximum number of digits that you can remember.


In this experiment, you will test how many digits people can remember.


Are you good at remembering a phone number? Most people don’t even remember phone numbers anymore, and instead program them into their phones. There is a limit to the number of numbers, or digits, that most people can remember. The longest string of numbers that anyone has ever memorized is for the number pi (3.14159265…). Akira Haraguchi from Japan set a new world record by memorizing the first 100,000 digits on Oct. 3rd, 2006. That’s a lot of digits!

Our memory is a function of our brain, which processes and stores information from the world around us using our five senses: sight, sound, smell, taste, and touch. The brain integrates these experiences into a memory. For some people, certain senses create stronger memory than other senses. There are even people who never forget a smell, and become perfume makers!

In this experiment, you will test the memory of your participants. You will have them remember sequences of numbers that they hear you read. You will test them and compare how many they get correct. This will test the digit span of your volunteers. How many numbers will they remember?

Terms and Concepts

To do this type of experiment you should know what the following terms mean. Have an adult help you search the internet, or take you to your local library to find out more!

  • memory
  • digits
  • sequence
  • random numbers
  • frequency


  • How many digits can people remember?
  • Will most people remember the same number of digits?
  • Are there other factors affecting digit memory, like age or gender?


  • computer with internet
  • index cards
  • plastic baggies and a shoe box
  • clipboard to hold data table

Experimental Procedure

  1. In this experiment, you will need number sequences for people to remember. Each number sequence should be composed of the numbers 0-9 and will be of different lengths. You will start with a sequence that is 2 digits long, and then 3, 4, or 5 digits until the volunteer can no longer remember a number. You can think them up yourself, or use this random number generator on the internet.
  2. If you choose to use the random number generator, use your browser to go to and fill out the form so that it looks like this:
  1. Then hit “Get Numbers” and a new page will appear with 7 listed numbers at the top. To get new numbers you do not need to fill out the form again, simply click the refresh button on your browser window, and voila! A new set of random numbers appears:

Here’s the 1st set I got:


And here’s the 2nd set I got:


4. On the first set of index cards, write two numbers on each card. These cards will be the first cards you read to your volunteer. Put them in a baggie labeled with the number 2.
5. On the next set of index cards, write three numbers on each card. These cards will be the second cards you read to your volunteer. Put them in a baggie labeled with the number 3.
6. On the next set of index cards, write four numbers on each card. These cards will be the third cards you read to your volunteer. Put them in a baggie labeled with the number 4.
7. On the next set of index cards, write five numbers on each card. These cards will be the fourth cards you read to your volunteer. Put them in a baggie labeled with the number 5.
8. On the next set of index cards, write six numbers on each card. These cards will be the fifth cards you read to your volunteer. Put them in a baggie labeled with the number 6.
9. On the next set of index cards, write seven numbers on each card. These cards will be the sixth cards you read to your volunteer. Put them in a baggie labeled with the number 7.
10. On the next set of index cards, write eight numbers on each card. These cards will be the seventh cards you read to your volunteer. Put them in a baggie labeled with the number 8.
11. On the next set of index cards, write nine numbers on each card. These cards will be the eighth cards you read to your volunteer. Put them in a baggie labeled with the number 9.
12. On the next set of index cards, write all ten numbers on each card. These cards will be the ninth cards you read to your volunteer. Put them in a baggie labeled with the number 10.
13. Collect your cards and organize them in a shoe box for easy transport and retrieval during your volunteer interviews.
14. You will also need a data table for your experiment. It should have a place to record the highest number of correct answers for each volunteer. Here is a data table where you put a check mark in the box for the participant each time they get the correct answers:

Volunteer Info:

Highest Number of Correct Answers:

Name Age Gender 1 2 3 4 5 6 7 8 9 10
  1. Find a research participant, and ask them if they will take a series of memory tests. Explain to them that you will read them a series of numbers slowly, and that then you would like them to tell you the numbers back in the same order that you read them.
  2. Beginning with the 2 number cards, read the numbers slowly and let the volunteer respond. If they get the numbers right, put a check in the box and then move on to the 3 number cards. If they get these numbers right, then check the box and move on until the volunteer misses a number. If the volunteer misses a series, then do not check the box of your data table.
  3. You will need to have a lot of participants for this study, so gather data from as many people as you can! When you are done, count up the total number of people who got each score on the test and make a frequency table:


Number of participants with this score

Percentage of participants with this score

  1. Calculate the percentage of people who received each score. Dothis by first adding the total number of participants for each column, then divide the number of people receiving the score by the total number of participants in your study.
  2. Analyze your data by making a histogram. On the left side of the graph (y-axis), write a scale for the percentage of people from zero to 100%. On the bottom of the graph, write a scale for the number of correct digits remembered from zero to ten. Then draw your results on the graph.

Balloon Powered Race Car

Balloon Powered Race Car Project


  • to create a balloon powered race car for maximum speed between 0 and 3 meters
  • to incorporate Newton’s Laws of Motion

Part 1 (20 points)

Newton’s three laws seem to work perfectly on the chalkboard, but in real life we find that surfaces are seldom frictionless and that few moving objects are truly predictable.  This is because outside forces interfere with Newton’s perfect situations.  Balloon racers rely on Newton’s third law of motion.  As the air rushes backward out of the balloon it pushes the car forward in the opposite direction with an equal force.  Your job is to make the most of this force!  While building balloon racers we will discover how difficult it can be to make something work reliably.


  1. Wheels –plastic bottle caps, cd’s, spools of thread; you may cut-out your own wheels from paper, plastic, Styrofoam, metal, etc…
  2. Axle rod – The rod is the part attached to two wheels so they turn in unison. Small diameter plastic straws, coffee stirrers work well.  You may cut them or use a material of your choice.
  3. Axle housing – You slip the rod through the housing and attach the housing to the car. Regular plastic straws work well. They can be cut to any size you want.
  4. Body – anything you want, popsicle stick, cardboard, styrofoam, balsa wood etc… 
  5. 9” Balloon
  6. Various materials to construct the racers, all materials must be “stuff” lying around your house or school (except for tape or glue)!
  7. tape and glue
  8. You will receive:

–          a 9-inch balloon

–          straws

–          (if you need materials or ideas let me know and I will help you out)

  • Design and contest rules
  1. No kits or pre-made designs may be used. The car must be the individual’s invention.
  2. The car must be completely powered by the balloon.
  3. All self provided materials must not be purchased specifically for this contest; use items you have around the house or if not, ask me for materials from school.
  4. The balloon can be inflated to any size as long as it does not burst. Should the balloon burst during the run, it will count as an official run.
  5. Only 9-inch (22.5 cm) latex balloons will be used during the competition.
  6. The car must have a minimum of three wheels.
  • Judging:
  1. Cars will be tested on a smooth flat surface. Distance is measured from the starting line to the farthest point of travel, utilizing a straight line to connect the two points.
  2. The car must move a minimum of 3 meters, in order for the score to be recorded.
  3. The score will be based on the speed of the car. In case of a tie, a race will be held.

Good Luck!

Part 1 continued: Building the Car : Tips and Tricks

  • The first thing to do is choose the material to build the body of the car.  The body should be both light and sturdy, for this reason styrofoam makes a very good body.  It is also important to design a body that is long enough.  Short cars tend to spin out more often than longer ones.  A good car should be about 30 cm long.
  • The second thing to do is build and mount the wheels.  Wheels can be made out of about anything that is round, such as CDs, caps, and lids.  The hard part, however, is getting them mounted straight with little friction.  If the wheels are not mounted straight or are not free to spin smoothly, the car will not perform.
  • Once the wheels are mounted on the body it is time to put a balloon onto the car.  Having the balloon attached to a pen barrel so that the air comes out in a smooth manner helps.
  • If the car has a sturdy but light body, free moving wheels and a good power supply, you are well on your way to being a balloon racer champion.
  • Tips for attaching balloons to tubes:
    • Make sure tube or straw goes all the way into the balloon (past the neck part and into the body) – this ensures that the balloon won’t fold and stop up the tube
    • Wrap the balloon around the tube end so that it basically seals and you end up with the balloon tightly wrapped around the tube with a flap of balloon left over on one side. Carefully fold the flap around the tube, keeping the seal good, and tape the flap to the rest of the balloon
  • Also, making sure the axles are parallel is key

Part 2 (10 points)

Sketch a diagram of your car on a separate piece of paper. Include the following;

  1. overall length of car
  2. overall width of car
  3. diameter of wheels
  4. length of axle housing
  5. length of axle rods
  6. Force arrows of all forces acting on the moving car
  7. Force arrows must be labeled

 Part 3 (20 points)

Each group member will write a five paragraph typed paper, describing how they used the science and       Newton’s Law’s of Motion to complete their project.

  • First paragraph- Describe the problem you are trying to solve. What are the rules you need to follow to complete the project?
  • Second paragraph- Describe how you solved the problem. What types of problems did you run into?  What process did you go through to complete your car successfully?
  • Third paragraph- Describe what build methods worked best. Specifically, discuss the competition; what traits made the fastest car? What would you have done differently?
  • Fourth paragraph- Describe how Newton’s Law’s of motion were at work on the car while in motion and during construction/design of your car. (Friction, Momentum, Forces etc…)
  • Fifth paragraph- In conclusion, describe what you learned by doing this project. Discuss the best parts of the project and the most difficult moments. Also, what would you do differently next time?

What you must hand in:

  1. Sketch of your car as described in Part 2
  2. 5 Paragraph paper as described in Part 3
  3. Complete answers to questions in procedure section Part 4
  4. Balloon racer car “ready to race” on race day.  Part 1
  5. Cover for written material

Procedure (you can use these steps as a guide or try to do it your own way):

1. Cut the bend off two regular plastic straws.

  • These are called the axle housings.
  • The housing should be slightly shorter than the axle rod (step 2).
  • Measure the length of your axle housing and record your measurement in cm. ______________cmAxle rods:
  • Measure the length of your axle rods, record your measurements in cm. ____________cm
  • Insert the axle rods into each axle housings.
  • You may want to glue one wheel onto each axle rod, then place the axle housing over the axle rod and glue the other wheel onto the axle rod.
  • Center axle housings onto the popsicle stick.
  • Put one axle in front and one in the back.
  • Use the hot glue gun to fit these pieces into place.
  1. Try your car.
  • Put it on the ground.
  • Give it a push.
  • Does it roll, easily?
  • If not, check to make certain your axle rod is not rubbing on the inside of the axle housing.
  • If rubbing is a problem, go see T. Joyce
  • Use the third regular-sized straw and insert about 2 cm of the straw, near the bend, in the opening/neck of a balloon (22.5 cm or 9 inch).
  • Secure the balloon in place by looping a small rubber band several times around the neck of the balloon containing the straw.
  • Make sure the rubber band does not crush the straw.
  • Tape the straw to the car – leave enough straw to blow into the balloon and fill the balloon with air.
  • To move the balloon car, blow into the free end of the long straw until the balloon is the desired size.
  • Quickly squeeze the opening of the straw to keep the air from escaping from the balloon.
  • Position the car, balloon end in the front.
  • The car should begin to travel as soon as you remove your finger from the straw.
  • If your car moves sluggishly or not at all, it is because the axle is rubbing and you did not adhere to the requirements of Step 6.
  • Use a ruler to measure the:
  • Overall length of your car (cm): _________
  • Use the digital scale to measure the overall weight of your car (grams): _________
  • Did you fill-in all the blank spaces on the previous 10 steps?

   Test your car.

  • Inflate the balloon without breaking it.
  • Hold the nozzle shut until you are ready to race.
  • Release the nozzle and start the stopwatch.
  • Stop the watch when the balloon runs out of air.
  • Mark the spot on the floor where that occurred.
  • Record your results on the data table.

Test Your Car


Your time

in seconds

Distance traveled

in meters



Run #1

Run #2

Run #3

Competition racing with group members in the hallway





Who’s car traveled the farthest? ______________________________

Who’s car traveled the fastest in the first 3 meters? ________________

Who’s car exhibited the fastest overall speed? ________________

Part 4  (5 points)


1.Does the length, width and weight of the car make a difference in its performance?  Explain by providing evidence from your races.

2.The key word in this project is friction. Did friction play a role in your races? Explain by providing evidence from your races.

3.  Look-up the word momentum.  Was momentum a factor in your races? Explain your thinking and provide evidence from your data to support your opinion.

The Balloon Car Race!

Rubric: 60 points total!


The car: (up to 20 points)

  • 20 points- The car follows all rules and travels 3 m with fastest speed
  • 19 Points- The car follows all rules and travels 3 m in the 2nd fastest speed
  • 18 Points- The car follows all rules and travels 3 m in the 3rd fastest Speed
  • 17 Points- The car follows all rules and travels 3 m
  • 15 Points- The car follows all rules and travels only 2 m
  • 14 Points- The car does not meet regulations or does not travel 2 m

 The car sketch: (up to 10 points)

  • All details in part 2 are in the sketch and legible
    • -1 point for each missing item from part 2

 The 5 paragraph paper: (up to 20 points)

  • 5 Points: Complete Paragraphs (at least 4 sentences per paragraph): (-1 for each missing paragraph)
  • 5 Points for perfect grammar and spelling (-.25 points for each error up to -3 points)
  • 10 Points did the writer address all questions as described in part 3 (-1 point for each missing question)

 The questions: (5 Points)

  • (-1 for each incomplete answer)

 Cover: ( 5 Points)

  • Name, Date, Class Period, Picture, Packet stapled correctly (-1 for each missing item)