Subitizing is all the rage right now! Student with strong number sense are able to quickly recognize numbers without counting. Use these cards as a quick math warm-up to help your students subitize with tally marks.
These cards show the numbers 1-75. Print them off, cut them in half and shuffle them to put them in a random order. Each day, "flash" a few cards using this procedure:
1.With your students sitting on the floor in front of you, flash a card for about 5 seconds (possibly longer when you are just beginning this routine).
2. Ask your students, "What number did you see? How do you know?" The second question is extremely important because it tells you HOW student are seeing numbers. Are they counting by 5s? Did they figure out a whole row is 25 and then count on? Students can discuss their thinking with a partner and then with the class.
3. Repeat this process with 2-3 cards per day.
You can also use these cards as a quick one-on-one assessment with your students. Flash a card and jot down how the student explains his/her thinking. 2nd graders could even express their thinking in writing. This is perfect for incorporating some of the Common Core Mathematical Practices:
#3 Construct viable arguments and critique the reasoning of others
#7 Look for and make use of structure
#8 Look for and express regularity in repeated reasoning
Let me know if your little mathematicians enjoy this routine as much as mine do!
Light Up the Classrom