Lesson Plan

Introduction to Algorithms

SWBAT describe the use and importance of Alogirthms
Robert P.
Technology coordinator
Broome Street Academy Charter High School
New York, United States
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My Grades 9, 10, 11, 12
My Subjects Science

Students will be able to...

  • vocalize and discuss their pre-existing knowledge of algorithms
  • create a prediction as to the definition of algorithms
  • work in groups to discuss and create algorithms
  • define and implement algorithms
Grades 9 – 12
All Notes
Teacher Notes
Student Notes

1 Do Now

Activity: Conversing

Circulate and support student discussion

Student Instructions

Silently find your seat.

Silently choose a partner

Quietly write down a definition in your own words for:
Computer Science

2 Agenda

Activity: Reading


Share the day's agenda with students.

Student Instructions


First 5: Do Now

5 minutes: Definitions

30 minutes : Writing an Algorithm

10 minutes: Discussion

3 Discussing the Do Now

Free to try, Paid

Prompt student discussions for five minutes

Play Flocabulary videos on Coding and Computer Programming



Students update written definitions

Prompt student discussions for five minutes

Student Instructions

Be ready to share your definitions during our discussion!

Watch these videos, paying particular attention to how they define the idea of "computer programs"

Use the information you learned from the video to rewrite your definitions.

Be ready to share out your new definitions with the class!


4 Building Connections

Activity: Investigating

Define Algorithm on the board

Ask students to draw connections between "Algorithm" and "Program"

Student Instructions

Rewrite the definition for Algorithm in your own words

How does this definition relate to your definition of "computer program"

5 Observe an Example

Activity: Presenting

Go through these steps one at a time- only show one step on the board.

Ask the students at each step if they know what the full "program" the algorithm is defining.     

 1) Go to bathroom
       2) Find toothpaste and toothbrush
       3) Turn water on
       4) Wet toothbrush head
       5) Turn water off
       6) Place toothpaste onto brush
       7) Turn water on
       8) Wet toothbrush with toothpaste
       9) Turn water off
       10) Begin to brush each tooth in your mouth for two minutes
       11) Rinse mouth
       12) Rinse toothbrush
       13) Return toothbrush and toothpaste to storage place
       14) Exit bathroom

At the end, explain that sometimes algorithms cover more actions than they initially seem to.

Student Instructions

I am going to show you an algorithm I follow each day, step-by-step. At each step, I want you to try to guess what activity my algorithm is working through.


What happens if I make one of the steps less specific?

6 Create Your Own Algorithms!

Activity: Creating

Circulate and support the students as they create their own algorithms.

Student Instructions

In a group of 4 students, write three algorithms that define activities in your daily lives. Make these algorithms as specific as possible.

7 Share-Out

Students share the name of their algorithms with the class.

Find a video of someone completing that activity.

Students share their algorithm, step-by-step.

At each step, show that step at the video.

Have students correct their algorithm in media res.

Student Instructions

Each group is going to share one of their algorithms with the class.

We will compare that algorithm with a video of a person completing that task.

Be ready to correct your algorithm!

8 Algorithm Debrief

Activity: Conversing

Allow students to discuss their answers- monitor and guide the discussion.

Student Instructions

What worked well?

What didn’t work so well?

How did we debug our algorithms?

How did we ITERATE to get closer to a solution?

What was the right level of detail for our “robot”?


9 Exit Ticket / Homework

Activity: Other — Concluding

Guide students through signing out and cleaning their space.

Explain student homework and expectations for the homework.

Student Instructions

Clean up your space and put your notebook away.


Here is your homework:



make a peanut butter and jelly sandwich.

The algorithm should have STEPS that I can do WITHOUT THINKING

I will “run” your algorithm

If your algorithm doesn’t work the way you intended, it has a BUG

We will debug our algorithms until they work!