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About this game
Evaluate expressions: a free Grade 6 math game for ages 11-12. Kids find the value of an expression like 2x + 7 for a given x. Each round brings 10 fresh questions with new numbers; instructions are read aloud and every answer is checked.
What is 3x + 5 when x = 8? Evaluate expressions asks exactly that, with a new expression and a new value of x on every card. The number in front of x runs from 2 to 9, x from 1 to 10, and the number added from 1 to 20. Ten cards make a round in this Grade 6 game; your child types the value, and each answer is checked, with a hint on each card.
Substitution is the first algebra move. The letter is a placeholder, so x = 8 means 8 takes its seat. The hint adds two rules worth repeating: a number next to x means multiply, and the multiplying comes before the adding. So 3x + 5 becomes 3 × 8 + 5, which is 24 + 5, or 29.
Writing numbers side by side is the slip here. With x = 8, 3x can turn into 38, and 38 + 5 gives 43. Ask, "Does 3x mean thirty-something, or three of x?" Rewriting it with a times sign clears it up. End with, "You put the times sign back in."