How Many More?
Students will be use subtraction to compare numbers.
- Ask students what subtraction is and what kinds of problems it can help solve. Take a few answers.
- If students don’t bring it up on their own, tell students that subtraction can be used to compare the size of different numbers.
Explicit Instruction/Teacher modeling(10 minutes)
- Use snap cubes to make a tower of 11 and a tower of 4.
- Show students the towers and say, “Subtraction can be used to figure out how many more 11 is than 4. I can subtract 11 - 4To find the difference between the two numbers.”
- Explain that 11 - 4Is 7. So, that means 11 is 7 more than 4.
Guided practise(10 minutes)
- Tell students that you are going to take a quick survey to see which one of the following colors the class likes best: Red, blue, or yellow.
- Write the colors on the board and leave room to draw vertical towers above them.
- Tell students they will raise their hands when you say the colour they like best (only voting once). As students raise their hands, draw equal size x’s above the colors to make a bar graph.
- Now ask, “How many more students like (name the most popular colour) than (name the least popular colour)?”
- Hand out snap cubes and have students compute the difference.
- Call the class back together and ask them to share their answers.
Independent working time(20 minutes)
- Hand out paper to each student. Tell them they will be working with a partner to create and implement a survey. Have them come up with a question that has three to four possible answers and represent the data they collect on a bar graph.
- When the bar graphs are completed, have students calculate how many more people liked the most popular answer than the least popular answer.
Enrichment:Have students create surveys and bar graphs with more than three to four possible answers.
Support:Have students use snap cubes when computing difference.
- Assess students’ understanding by observing both how they create bar graphs and how they compute differences.
Review and closing(5 minutes)
- Call on a few pairs of students to share about their surveys and the data they collected. Be sure that they share the difference between the number of people who liked the most popular answer and the number of people who liked the least popular answer.