Objective:

Students will learn how to associate characters with numbers and use simple arithmetic operations (addition, subtraction, etc.) to create and decode secret messages. Through this activity, students will practice computational thinking by transforming data and solving problems.

Materials Needed:

• A character-to-number conversion table (A=1, B=2, C=3, etc.)

• Pencils and paper for students to write their secret messages

• Arithmetic problems (addition, subtraction, multiplication, division)

Steps:

• Introduction:

  • Begin by introducing the concept of codes and secret messages. 

  • Ask, "Have you ever wanted to send a secret message to a friend?" 

  • Explain that they will be using math to convert letters into numbers and then perform arithmetic operations to create secret messages.

• Group Activity:

  • Divide students into pairs. 

  • Each student will choose a short word or sentence, convert each letter to a number using the character-to-number table, and then apply an arithmetic operation (e.g., add 2 to each number). 

  • They will then write down the transformed numbers as their secret message.

• Testing and Decoding:

  • Partners will swap secret messages. 

  • Using the inverse operation (e.g., subtracting 2), they will decode the message by reversing the arithmetic operation and converting the numbers back into letters. 

  • The students will check their decoded message with their partner to see if they were able to crack the code.

• Presentation and Discussion:

  • Each pair will present their secret message and explain how they created and decoded it using math. 

  • Lead a class discussion on how using math can change and transform information and the importance of patterns in encoding and decoding messages.

Equity and Access:

Provide visual aids such as a character-to-number conversion chart and example arithmetic problems. Pair students with varying math abilities to ensure collaboration and support.

Real-World Application:

Discuss how codes and secret messages are used in real life, such as in spy movies or to protect important information online. Relate this to how computers encode and decode information for security purposes.

CS Practice(s):

• Recognizing and Defining Computational Problems: Students identify how to transform characters into numbers and use operations to encode messages.

• Developing and Using Abstractions: Students abstract letters into numbers and manipulate them mathematically to create coded messages.

Standard(s):

• CA CCSS for Mathematics 2.OA.A.1

• CA CCSS for Mathematics 2.OA.B.2

• CA CS K-2.NI.6

Objective:

Students will use a digital tool such as Google Sheets to create a character-to-number conversion table and perform arithmetic operations to encode and decode secret messages. This activity integrates computational thinking and technology skills.

Materials Needed:

• Tablets or computers with access to Google Sheets or another spreadsheet program

• Pre-made character-to-number conversion table template in the spreadsheet

Steps:

• Introduction:

  • Begin by discussing how computers use codes to protect information. 

  • Introduce the idea of using a digital tool like spreadsheets to create secret messages. 

  • Explain that students will use a conversion table and simple math functions to encode messages.

• Group Activity:

  • In pairs, students will access a pre-made spreadsheet template with a character-to-number conversion table. 

  • Each student will type a word into the spreadsheet, and the table will automatically convert the letters into numbers. 

  • They will then apply a mathematical operation (e.g., add 5 to each number) by using a function in the spreadsheet to create a secret message.

• Testing and Decoding:

  • Students will swap secret messages with their partners, who will use inverse operations (e.g., subtracting 5) within the spreadsheet to decode the message. 

  • Once decoded, they will convert the numbers back into letters using the table and check if they have cracked the code correctly.

• Presentation and Discussion:

  • Students will present their secret messages and demonstrate how they encoded and decoded them using spreadsheet software. 

  • Lead a discussion on how computers use encryption to protect data and how mathematical functions are used in coding.

Equity and Access:

Provide step-by-step instructions for using spreadsheets and support for students unfamiliar with the program. Pair students with varying experience levels to encourage peer support.

Real-World Application:

Explain how encryption is used in everyday life to protect sensitive information, such as passwords or credit card details. Connect the lesson to how computers store, transmit, and protect data using similar methods.

CS Practice(s):

• Creating Computational Artifacts: Students use spreadsheets to encode and decode secret messages by applying mathematical functions.

• Testing and Refining Computational Artifacts: Students test their encoded messages by swapping with peers and decoding them, refining the process as needed.

Standard(s):

• CA CCSS for Mathematics 2.OA.A.1

• CA CCSS for Mathematics 2.OA.B.2

• CA CS K-2.NI.6