Binary Numbers: Counting with Only 0 and 1

SubstitutePlans.com
Technology and Computer Science · Computer Science
SP-CS-002 · Free to print and use in your classroom · substituteplans.com
Page 2
Binary Numbers: Counting with Only 0 and 1
Technology and Computer Science · Computer Science · Grades 8-10 · 50 minutes
Time needed
50 minutes (one class period)
Prep
Copy the 2-page worksheet (one per student). Write the place-value row on the board.
Technology
None. Calculators are not needed.
Student
independence
High. Students work alone with a short partner check.
Copies to make
One 2-page worksheet per student
Materials
Pencils, Worksheet, Whiteboard or chalkboard
Goal for today: Students will convert whole numbers between binary and decimal using place values and will add two
small binary numbers.
Before the bell
☐ Copy the worksheet, one per student (2 pages).
☐ Write on the board: 128 64 32 16 8 4 2 1 (these are the place values in an 8-digit binary number).
☐ Write the example: binary 1011 = 8 + 2 + 1 = 11.
☐ Keep the answer key on your desk. You do not need to know any computer science.
Say this to start
Computers store everything using only two symbols, 0 and 1. That system is called binary. Today you will learn to read
and write binary numbers using a simple chart. It works like place value in regular numbers, except each place is worth
double the one to its right. Take it step by step and check each answer by adding the values back up.

SubstitutePlans.com
Technology and Computer Science · Computer Science
SP-CS-002 · Free to print and use in your classroom · substituteplans.com
Page 3
Run of show
Minutes
What you do
What students do
0–5
Take attendance. Hand out the worksheet and ask
students to read the box at the top.
Read “How binary works.”
5–13
Read this example aloud from the board: “To read 1011,
line the digits up under the chart from the right. The 1s sit
under 8, 2 and 1. Add them: 8 + 2 + 1 = 11.” Then show
going the other way: “To write 13, take the biggest value
that fits, 8. That leaves 5. Take 4, leaving 1. Take 1. So 13
is 8 + 4 + 1, which is 1101.”
Follow along and copy the two examples in
the margin if they like.
13–33
Tell students to work Parts A and B (questions 1 through
10) by themselves. Walk around. If a student is stuck, ask:
“What is the biggest place value that fits?”
Convert binary to decimal, then decimal to
binary, using the chart.
33–43
Tell students to finish Part C (questions 11 through 17). Let
partners compare answers on question 14 only.
Answer the fill-in, secret word, addition and
multiple choice questions.
43–47
Read the answers for questions 1 through 10 aloud from
the key. Students mark their own work.
Check answers and fix mistakes.
47–50
Have students complete the exit ticket, then collect all
worksheets.
Write the exit ticket sentence and hand in
the paper.
If things go wrong
• If a student says, “I do not get it,” point to the example on the board and ask them to add up the place values
for just the 1s.
• If a student writes the number backward, remind them that the right-hand digit is worth 1, not the left-hand
one.
• If the class is noisy, remind them that this is individual practice and partners may whisper only for question
14.
• If a student wants a calculator, say it is fine to check addition, but the conversions should be done with the
chart.
Early finishers
• Write the binary numbers for your age and for the number of students in this room.
• Count in binary from 0 to 10 on the back of the paper.
Support and challenge
• Support: Let students write the place values over each digit before adding. Have them do questions 1, 2, 3, 6,
7, 8 and 16.
• Challenge: Ask students what the largest number is with 10 binary digits, and how they know (hint: 2 raised
to the 10th power minus 1).

SubstitutePlans.com
Technology and Computer Science · Computer Science
SP-CS-002 · Free to print and use in your classroom · substituteplans.com
Page 4
Notes for the teacher (you fill this in)
Jot a few lines before you leave. A full Daily Sub Report is in the free Sub Survival Kit at SubstitutePlans.com.
How far the class got / what to pick up next:
Students who were especially helpful:
Anything the teacher should know: