Turning a str Into a float

The Python programming language uses data types to distinguish between different types of information.

Dependencies

Students need to have these skills before learning this skill:

• Taking User Input
• The float Data Type

Goal

When you teach this skill, your goal is to make it so that students can write code that looks like this:

number_1 = input("Enter a number: ")
number_1 = float(number_1)
number_2 = input("Enter a second number: ")
number_2 = float(number_2)

print("Total:")
print(number_1 + number_2)

Activities

Here are some activities that you can do in order to teach this skill.

Why does this code break?

1. Write this code on the board:

   number = input("Enter a number: ")
   print(number + 1)

2. Ask students what they think that code will do.

3. Run the code.

4. Ask students why the code broke. After calling on a few students, reveal the correct answer.

5. Change the code to fix the problem:

   number = input("Enter a number: ")
   number = float(number)
   print(number + 1)

6. Explain how your changes fix the problem.

7. Have students write a similar program on their computers.