Introduction: Makey Makey Stopwatch

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Stop. Stop! STOP!

An essential scientific skill is being able to use a stop watch. Inaccuracy in starting and stopping can hinder data results and thus the outcome of scientific experiments.

As this skill is quite complicated for primary students, due to their reaction/response time, I have created an electronic stop watch to use with younger students as a stand alone timer or back up.

Supplies

  • Makey Makey
  • Cardboard or timber
  • Sticky tape
  • Alfoil or copper tape
  • Wire
  • 2 pens/pencils
  • Computer
  • Scratch program

Step 1: Ramp

Cut cardboard or timber to the desired length to make a ramp. The longer the ramp the more accurate the result due to the timer only being in seconds.

Make sure there is a flat surface at the start of the ramp, sides to contain the item being rolled and a flat finish with a wall to stop the item rolling, so it activates the "Stop Timer" switch.

Place a wide strip of alfoil at the start of the ramps flat platform, which will be the "Reset Timer" switch.

Place a thin narrow strip at the top of the ramp as the "Start Timer" switch.

Place a strip of foil at the end of the ramp which will act as the "Stop Timer" switch.

The switches will be activated by the earth on the See-Saw switches.

Step 2: See-Saw Switches

Start Switch

Cut a piece of card to act as the see-saw switch at the start of the ramp. It needs to be long enough to allow either end to touch the two pieces of foil on the platform and wide enough so items of various sizes can be place on it.

Run a piece of alfoil from tip to tip on the ramp to act as the earth.

Finally stick a pen or pencil to the underside closest to the start of the platform.

When an item is placed on the end of the see-saw switch it will cause the reset to be activated, ready to start the timer. When the item being timed is gently rolled forwards it will tip the seesaw and activate the start stopwatch and the item will begin rolling.

Finish Switch

Cut your card the width of the ramp so the item must run over it at the bottom, even if it goes off course and hits the side.

A strip of alfoil is only needed at the far end of the see-saw where it will touch the "Stop Timer" strip of foil, alternately a flap switch would be more suitable with an earth on the finish wall and a curtain of alfoil hanging about 1 cm off it so that it will always be activated as the item rolls off the ramp.

Stick a pencil or pen to the see-saws underside to allow it to pivot.

The pivot points will have to be altered according to your individual ramp. The See-Saw switch MUST BE touching the narrow strip at the top of the ramp in its resting position and the finish see-saw switch MUST BE touching the ramp in its resting position NOT on the alfoil strip.

Step 3: Makey Makey Cables

The Start See-Saw is connected to the Makey Makey earth by the lime green wire.

The "Reset" switch (wide alfoil) is connected by the dark green wire to the space bar on the Makey Makey.

The "Start Stopwatch" switch (narrow alfoil strip) is connected by the red wire to the up arrow.

The Finish See-Saw is connected to the Makey Makey earth by the grey and white cables joined (2 cables were needed to reach the finish line.)

The "Stop Stopwatch" switch (alfoil strip at the end of ramp) is connected by the orange and yellow wires joined.

Make sure the clips on the See-Saw switch do not hinder the tilting of the ramp.

Step 4: Trial Prototype One

Finally connect the Makey Makey to your computer and click on the scratch link to begin timing.

https://scratch.mit.edu/projects/449157873