3rd Grade Math Question of the Day

1. 7 kg (correct answer)
2. 10 kg
3. 3 kg
4. 7 g

Explanation: This question tests 3rd grade measurement: measuring and calculating with mass (grams, kilograms) and volume (liters), and solving one-step word problems (CCSS.3.MD.2). Mass measures how heavy something is. We use grams for lighter objects and kilograms for heavier objects (1 kg = 1000 g). Volume measures how much liquid something holds, using liters. To solve measurement word problems, identify the operation (add, subtract, multiply, divide) and make sure units are the same. The problem states Marcus has a 5 kg backpack and adds a 2 kg lunch bag, asking for the total mass. Choice B is correct because 5 kg + 2 kg = 7 kg, demonstrating addition of masses in the same unit, like packing school items where a full backpack might weigh about that much. Choice D represents a unit confusion error by using grams instead of kilograms; this typically happens because students mix up units, as 7 g would be too light like a small eraser. To help students: Provide hands-on measurement experiences using scales (balance and digital) and measuring cups/beakers. Have students hold objects and estimate mass before measuring. Create reference points ('A pencil is about 10 grams, a textbook is about 500 grams, I weigh about 35 kilograms'). Use real containers to understand liters (water bottle = 1 liter, juice box = smaller). Practice with manipulatives and real measurements. Watch for: Students who don't include units in answers, students who use unrealistic measurements (person weighing 5 g), students who confuse grams and kilograms, and students who don't convert units when needed (adding 2 kg + 500 g without converting to same unit).