To begin the class, ask students to name the models for subtraction (counting backward, set, number line, balance, and inverse of addition) used during this unit. Then name a difference and have the children use pairs of connecting cube trains to represent that difference.
Next, ask the students to write two numbers that are less than 10 (for example, 5 and 7) on each of four index cards. Collect and shuffle the cards, and call on individuals to select two cards and find the difference between the numbers using any of the models studied in the unit.
Now assign students to work at one of the following five stations that you have set up in advance. Encourage students to visit at least three of the stations during the remainder of the class time.
Materials: cards with one digit numbers on them, paper
Using the cards generated by the students at the beginning of the lesson, have the children distribute the cards equally among four players. Each child displays one of the cards and the children find all the differences indicated. The children who displayed the card with the greatest difference make a tally mark. If more than one player displayed a card with the greatest difference,
each player makes a tally mark. Play continues until one child has eight tally marks.
Materials: connecting cubes, paper, number cubes
Provide each player with 2 number cubes and 12 connecting cubes. The players roll the number cubes, make a train that has as many cubes as the sum of the numbers thrown, and then compare the trains. The player with the longest train makes a tally mark on a piece of paper. After 10 rounds, the players compare their tallies; the one with the most tallies wins the game.
Materials: 21 pennies per player, paper
Give each pair of players a bag containing 21 pennies. Assign one player in each team to count heads, and the other to count tails. Have the children toss the pennies and count how many of their assigned sides came up. The child with more sides announces how many more heads or tails were counted and records that amount on a score sheet. The first child to reach or pass 25 wins the round.
Materials: 20 counters per team, brightly colored paper, coin
Distribute to each team a coin, 20 small counters, and a brightly colored sheet of paper. Have players choose “heads” or “tails” and flip a coin to decide
who will count those counters that land on the paper. The other child will count those that land off the paper. The children take turns dropping the counters, with the child who won the coin toss dropping first. After each drop, the
players count their designated counters and compare the numbers. The player whose group is greater records the difference between the groups as a score for that round. The play continues for 10 rounds, and the child with the highest score wins the game.
Materials: Bag of 20
connecting cubes with 5 each of 4 colors, crayons to match the 4 colors, Grid Paper for a bar graph
Prepare a bag of cubes with 5 each of 4 colors of cubes. Give the bag, some crayons, and Grid Paper on which they can make a bar graph to the players. Assign each child one of the colors in the bag and have the children pull a cube from the bag, color an appropriate square on a grid, and replace the cube. Tell them to make 20 draws in all and then compare the bars on the graph. The player whose
color has been drawn the most often wins the round.
Materials: Race to Zero Activity Sheet, Number cubes
Tell students they are to take turns rolling a number cube and subtracting the number they rolled each time from 20. The first child to reach 0 wins the round. They should record the results on the
Race to Zero Activity Sheet.
You may wish to document specific models of subtraction that students understand and apply.
After the students have had time at the stations, call them together and ask them to record in their journals what happened when they played one of the games.
As another summative assessment activity, display two trains of connecting cubes and have the children compare them, recording the results in both vertical and horizontal notation. Then write a number less than 5 and have the students create two trains showing that difference.
