Students will be able to mentally find 10 more or 10 less than a given two-digit number without counting.
The adjustment to the whole group lesson is a modification to differentiate for children who are English learners.
Call students together around the hundreds chart.
If you have wardrobe items, wear them.
Tell your students that today they are going to be math magicians. In order to perform this magic trick, inform them that they will need some props.
Hand out lots of index cards to each student.
Instruct your students to write a number between 10-90 on one side of each card. On the other side of the cards, have the students write a plus sign with the number 10 and a minus sign with the number 10.
Demonstrate this process for students. Explain that they can count or use the hundreds chart to figure out what number is 10 greater (more) or 10 less (smaller).
Put a sticky note on the numbers 10 and 90 on a number line. Gesture at the numbers in the middle as you say, "between."
Create an anchor chart for reference. Write, "+ plus sign more" and "- minus sign less".
Show students how to form a plus sign with both arms as they repeat, "plus sign." Next, gesture with hands far apart and have them repeat in a loud voice, "more."
Tell them to gesture with one arm parallel to the ground as they repeat, "minus sign," and then gesture with hands close together as they repeat in a soft voice, "less."
Add further math symbols to the chart as they are introduced in subsequent lessons.
Invite students to share ideas for figuring out what number is 10 greater or 10 less than a given number. Record student ideas on the board before suggesting that they count on or use the hundreds chart (if students do not suggest these strategies).