When there is an addition symbol to the left of the parentheses, you can remove the parentheses. If you have a subtraction symbol instead, you can remove the parentheses, after you have altered the sign -- positive or negative -- of the terms within the parentheses. Prepare a worksheet containing a list of 10 math problems with grouping symbols, such as "5 + (15 - 7)" and "170 - (100 - 1)." Make a copy for each student, distribute the sheets in class and ask children to work alone to remove the symbols as fast as they can. The first student to solve all problems correctly is the winner.
When you must multiply the contents of a group with another number, you cannot remove the grouping symbols. Instead, you must expand the expression by multiplying the number directly outside the symbols with each and every term within the symbols. Write a complicated problem, such as "5(15 + 4 - 2 -2x)" on the top and right side of the board. Ask two students to come to the board and, on your mark, start expanding the expression. The first student to expand it moves on to the next round. Create a mini tournament of face-off matches, to determine the grouping symbols champion among the students.
Instead of expanding an expression, students must group the terms this time. To do this, they need to find a common denominator for all numbers of an expression. For example, in 6x - 12 + 18, a common denominator is 2 and the expression becomes 2(3x - 6 + 9), but also 3, with the expression becoming 3(2x - 4 + 6). Divide the class into groups of four. Write a series of expressions on the board, featuring more than one common denominator and allow children two minutes to find and write the new expressions. The team with the most correct answers is the winners of the round.
When you have a grouped section containing parentheses, brackets and braces and it's preceded by an addition or subtraction symbol, you can follow any route you want to remove the grouping symbols. Divide the class into teams of five and give them one complicated section that includes all three grouping symbols, such as 5 - {27 + 8 - [32 - (4 + 21)] + 4}. Ask teams to write down the six different ways of removing the grouping symbols on a sheet of paper and give it to you in less than four minutes. The fastest team to write down all six ways correctly is the winners.