During their 5th grade math curriculum, my students have been introduced to decimals. Today's Do Now assesses their prior knowledge of decimals and place value.
For each pair of numbers, determine <, >, or =
1) 2.914 ____ 2.91
2) 47 ____ 47.00000
3) 8.3214 ____ 8.3241
My students will have 3 - 5 minutes to complete the problems. After this time, I will randomly call students to the board to show their answers and explain their reasoning. As students share their reasoning, I will be listening for their understanding of place value. I will also help them to use appropriate mathematical vocabulary in their explanations (MP6).
This activity has been revised from the CMP3 Curriculum.
The Adding & Subtracting Card Sort Activity is designed to help students further understand place value. During the activity students make connections between the decimal and fraction representations of a number. They use their understanding of place value to add and subtract fractions. I highlight the connection for my students by saying that, "You will use your understanding of fractions to better understand decimals." I find that my students gain confidence working with decimals as they increase their understanding of the equivalence of fractional and decimal representations of numbers.
Teacher's Note: This activity is from the CMP3 Curriculum which we use in my school.
To get the Activity started I give each group of students a set of Adding & Subtracting Cards. I try to pre-cut the cards for my students to save time for mathematical reasoning, but this is not always possible. Then, I give my students the following directions:
I give my students about 20 minutes to work through the activity. As students work, I circulate throughout the classroom to assess their understanding. It is typical for groups to struggle with some of the cards, but it's important to let them work together to complete the activity (See Card Sort Activity video).
We will review the Card Sort Activity using a class discussion. I will ask some leading questions to motivate groups to share their thoughts and strategies.
Students may respond with different answers. Some groups may realize through the class discussion that some of their card groups can be combined.
It's best to start with one group of students and have them share a set of cards that they matched, while other students see if they've matched the same cards. Students should explain their thought process and strategies. I will call on several groups to answer this question, because it is helpful for students to hear different strategies.
If there are students who disagree that a card fits in a group, it is important to discuss the different interpretations of the card. It is possible that the students have made a mathematical error. I prefer to discuss the groupings, rather than to provide an answer key. I like to let my class discuss the cards until they've agreed upon the answers. When we do, it is usually because we have found the correct groupings.
Towards the end of the discussion I will select various students to show the groupings on the board and we will agree on the final groupings (See Card Sort Student Work). By the end of the discussion, it should be revealed that students can use the denominator of the fractions to determine the place value of the decimal. To bring the discussion to closure I like to ask the following question:
Students should realize that they can convert the decimals to fractions and use their prior knowledge of adding/subtracting fractions.
As an assessment of my students' understanding of the content in today's lesson, I will give them a problem to complete. After 5 minutes, I will collect their work and use my assessment of it to prepare for future lessons.
Using a fraction strategy to find the following sum:
8.9 + 2.43 =
If students complete the task quickly, I will encourage them to try to check their answer by adding the numbers as decimals.