Solving Word Problems with Positive and Negative Fractions

This lesson teaches how to solve word problems involving positive and negative fractions using mathematical reasoning. It highlights common mistakes students make, such as providing unreasonable answers. The lesson uses a cupcake recipe example to demonstrate solving a problem by doubling the recipe and using proportions. It emphasizes the importance of ensuring the solution is reasonable and answers the original question, concluding that Janie needs an additional 1 1/2 cups of sugar to make 36 cupcakes.

What is a common mistake students make when solving word problems with fractions?

• They use the wrong units.

• They don't check if their answer is reasonable.

• They use negative numbers incorrectly.

• They forget to multiply.

If Janie wants to double her cupcake recipe, how much sugar will she need in total?

• 4 cups

• 3 1/2 cups

• 3 cups

• 2 cups

What is the first step in solving the cupcake problem using proportions?

• Add the fractions together.

• Subtract the available sugar.

• Set up a proportion equation.

• Convert the fractions to decimals.

How much additional sugar does Janie need after considering what she already has?

• 1 cup

• 1 1/2 cups

• 2 1/2 cups

• 2 cups

Why is it important to revisit the original question after solving a word problem?

• To ensure the units are correct.

• To check for any spelling errors.

• To confirm the answer addresses the question asked.

• To verify the calculations.