Build a Marble Auto 2 BIT ADDER - Homeschool Digital Logic #11
Channel: Masked Marble
Date: 2021-07-15

Welcome to lesson 11 of GraviCalc Marble Run Computers, where each week we build a working digital logic computer circuit using GraviTrax marble runs. We’re doing this to learn how computers and other electronics work deep down inside.

A great STEM homeschool activity recommended for ages 8 and up. And in true homeschool fashion, we'll throw in a smattering of other topics like Christian theology, physics, math, and more, because our learning should always be cross-pollinated to be most fruitful.

Lesson 11: Fully Automatic 2 Bit Adder with Auto-Loading Carry Bit. Build this week's GraviCalc marble computer that adds two 2 bit (binary digit) numbers. And this computer incorporates a fun GraviTrax trick of loading a volcano!

GraviTrax sets required: 
* Two GraviTrax Starter Sets (Starter, XXL, Obstacle, or Speed , but unfortunately not Vertical Pro)
* One GraviTrax scoop
* One GraviTrax volcano

Get build instructions for this week's marble computer by entering this code into the Ravensburger GraviTrax app: AOI4WEA393
Or use this direct link: https://gravitrax.link.ravensburger.com/code/AOI4WEA393

Print the blank 2 Bit Adder Logic Table for your kids to fill out as they run the 2 Bit Adder Marble Computer:  https://docs.google.com/spreadsheets/d/1lvDO9m6PtUR52LsYkyUqsT232S4D7ucY7h5dHtxrO4M/edit?usp=sharing

Video of Andreas Schliefenbaum's original 3-bit GraviTrax adder, whose dual-switch adding process greatly simplifies the full adder compared to implementing it with 5 logic gates. His design was improved on for the marble computer in this video.
Andreas' video: https://youtu.be/L0pa2vswWb4

Video shot on iPhone SE (2020) using DJI OM 4 stabilizer. Video processed in iMovie for iOS. Table graphics generated in Google Sheets app. Cover photo assembled in BeFunky Photo Editor

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