Two Discs and a Shape Row

In the picture

1. 1A blue triangle on the outer rim: one symbol from the first set.
2. 2A red crescent on the inner rim: the symbol put in its place.
3. 3The pointer at the center: it marks the pair of symbols that match.
4. 4A circle bead repeated in the row: repetition that can point back to the same original symbol.

Examples

• A secret club replaces each letter with a shape.
• A cereal box decoder ring swaps letters for symbols.

Quiz: Two Discs and a Shape Row (Age 12)

1. 1

   What does a substitution code do?

   • It keeps every symbol exactly the same.
   • It swaps each symbol for another symbol.
   • It removes all repeated symbols from a message.
2. 2

   If a symbol repeats in a coded message, what does that most likely mean?

   • The repeated symbol stands for nothing.
   • The same original symbol likely repeats in the original message.
   • The original message has no repeated symbols.
3. 3

   When you use a two-disc substitution tool, what does the pointer mark?

   • The original message written in plain words.
   • The number of beads in the row.
   • The pair of symbols that match.

The answers, each with its explanation, are in the app. This lesson has left the free week, so its quiz is part of the subscription.