Kindergarteners are active little people. They love to move, and this activity lets them be wild and wiggly and reinforces the concept of numbers as quantity. Cut a large plus sign, minus sign and equals sign out of poster board or construction paper. Assign one child the task of holding each sign. The rest of the class should line up. Call out partial number sentences, like "2 + 3." The first two kids in line will hop to the front of the class, followed by the child with the plus sign, the next three kids and the child holding the equals sign. Have the "numeral" kids count off to figure out the answer, and the next five kids will come up and stand after the equals sign. Have the class repeat the entire number sentence, "2 + 3 = 5" together. The numerals return to the back of the line. Repeat this until each child has had a chance to be a numeral at least once.
This activity allows kids to sit at their desks but still be active and engaged. Give each child a number of manipulatives (small objects such as plastic cubes, animals, or chips); 20 should be plenty for kindergarten number sentences. Write a number sentence on the board and say it aloud. Each child should use their manipulatives to illustrate the sentence. For example, if the sentence is 3-1=2, the children will place three manipulatives in a pile, remove one, and be left with two.
This activity is similar to Addition Hop. Have the class line up and call out subtraction number sentences. As you do, the kids skip to the front of the class and act out the sentence. If you call out, "5 - 2 = 3," the first five kids skip to the front and call out, "Five!" The first three kids in that group then call out "Minus three!" and skip to the end of the line. The remaining kids call out "Equals two!" and go back to the line. Repeat until all the kids have had a turn.
Many kids are visual learners. That means that they learn best by seeing what they are being taught. Print out worksheets with number sentences on them. The numbers and symbols should be printed in a font that has them outlined in black and blank in the center. Let the kids color them in. This allows them to focus on the number sentences and remember them, and also helps improve hand-eye coordination as they color in the numbers.