How to Use Clocks to Teach Fractions
I just recently revisited one of my favorite lessons due to teacher request. I used to teach in a Title I school last year, but now teach in a more affluent area. I found myself teaching differently with the new set of students. Still, this lesson is one of my favorites, and helped 100% of students answer one of our practice standardized test questions (we are taking the ACT Aspire this year). First, I copy clocks on three different colors of paper for the students. Students get 3 different colored clocks each.
I pose questions to get the students to think about how we would cut the clocks into halves, fourths, and thirds. I found with the new group of students they had more intuition to think about how to divide the clock–reasoning about a clock face containing 60 minutes. Next, I questioned them about how we could divide the clocks into halves. This was easy for students. They knew we could split the clock into 30 minutes for each half.
Because halves relate well to fourths, through discussion I had students break their next clock into fourths. Sometimes there is a misconception when students break a clock into quarters or fourths because there are four quarters in a dollar. Students want to start their sections dividing on the four. This didn’t happen in this case however. Students knew that they could split the circle on the 3, 6, 9, and 12.
Next, I had students divide a clock to make thirds. This is always more of a challenge to students because thirds are not multiples of twos. I allow students to have a little group discussion at this point among themselves because they are unsure of how to divide the clock into thirds. When I remind them that the clock face contains 60 minutes, suddenly, they realize that they can divide the 60 minutes on the clock face into three parts on the clock face into equal 20 minute sections. Some also realize that they can take the 12 numbers and divide them into 3 equal parts which places four number sections in each part. The kids say, “Oh! It’s like a peace sign!”
From here, I have students do a worksheet which asks them questions about fractional parts of a clock. For example, what is 2/4 of an hour? ¾ of an hour? ⅔? And we explore how the size of the whole affects the size of the fraction when times smaller than a whole are used. Read here if you want to know more about this lesson.
If you want materials for this lesson, go here: