4th Grade Math Problem - Weight and Mass

Question

I may be overthinking this but something doesn't seem right. So in my daughters remote class today they are talking about weight and mass. The first question is

How many beans did it take to make 1 gram? Teachers shows a bag with one bean in it and says 1 bean = one gram.

Next question is

How many beans are there in the 1-ounce bag? She holds up a bag and says there are four beans in the one ounce bag. So answer is four according to the teacher. Is there not 28 grams (beans) in an ounce?

Last question is

There are 16 ounces in a pound. Write and solve a multiplication equation to show how many beans there are in your pound bag without counting them.

By reading that I would think they would want you to take four grams (which is what they are saying is an ounce) and multiply by 16 to get the answer. So 64. But she holds up a pound bag and there are clearly more than 64 beans in it. More around the 448 (16x28) give or take obviously based on actual weight of each bean.

So would you assume she meant to have 28 beans in the one ounce bag? Am i missing something or overthinking this?

Any help in this would be greatly appreciated. :)

Struggling Dad

Answer 1

You could also see this in another aspect:

1 bean = 1 gram

4 bean = 1 ounce

Try to keep this simplified, the teacher might be substituting the actual weight for the amount of beans. So you could go on the technical side and find the exact number of beans it would take to make an ounce but the first question might be introducing the student to this idea of substituting the actual weight with beans and the second question is providing you with the conversion necessary to answer the last question.

if we look at this from the teachers provided clues. She doesn’t want you to find the exact bean count for 1 ounce she already provided that by holding up the 1 ounce bag and telling you exactly how many beans are in it.

4 beans = 1 ounce

16 ounces x 4 beans = 64 beans (1 lb)

Though this could go both ways, it just depends on which direction the teacher was aiming for. It could either be a mistake or intentional. I’d say reaching out to the teacher would be the best next option.

Let me know if you need any further help!

Answer 2

I would agree with you. Perhaps she made a mistake saying

4 beans in one ounce

If each bean weighed 1 gram

then

28.35 beans would make one ounce

and then

453.59 grams would make one pound

She probably rounded the beans to

28 beans in one ounce

and

448 beans in one pound

We all make mistakes. This is why it is nice to see the equations as in your thinking above

1 bean 1 gram

1 ounce is equal to approx. 28 grams

? wouldn't that be 28 beans to make an ounce?

then

1 pound equals 16 ounces

so would the math be

16 x 28 = 448

448 beans equal one pound

Is she using all the same size/weight beans?

This question might be a way to approach your concussion with the teacher, THEN SHOW HER YOUR MATH.