Okay, I feel like a moran, but this is my first year teaching 4 grade after many years in 6 grade where I did not teach science (we team taught).. How do I explain the difference between mass and volume of matter to fourth graders so they understand it? Any good suggestions?

Thanks.
Jessi

[googiesk]

When we study density we need to know mass and volume. I make an analogy of mass being amount of students in the room and volume is the size of the room. And then we discuss what if we make the room smaller--would we get more squished or less squished (density). I don't know if this helps you or not but it helps my students visualize it. Also, I would take out the triple-beam balance and have students measure mass and then take out a ruler or graduated cylinder to measure volume. Bring food items to class and have students read the label to find out it's volume (and sometimes mass is on there too) so they get an idea of different volume sizes. Definitely hands on activities exploring mass and volume really helps students to see the difference.

[roo]

Do you mean the difference between mass & weight? Mass and volume are actually quite different. Volume is the number of cubic units needed to fill a solid or container. You can find mass by counting cubes or multiplying LxWxH. Volume will be expressed in cubic centimeters, cubic inches, etc. For instance, if you had a rectangular prism shaped box, you could use a ruler to find a length (let's say 10 cm), width (let's say 4 cm) and height (let's say 5 cm), so you'd multiply 10x4x5=200 cubic cm.
For mass, that's the amount of matter in something. Mass would be measured using a scale or maybe a double pan balance. It could be expressed in grams or kilograms (occasionally seen using the US system, but mostly metric). It is similar to weight, except mass is a constant. It will not change because of other variables. Weight can change with other variables introduced. For instance my mass would be the same on Earth and on the moon. My weight would change from Earth to the moon because of the lack of gravity on the moon.
Hope this helps.

[kmob]

I have been teaching 4th grade for 8 years now, and I have two experiments I do to help understand these concepts. As they often get confused between mass being how much matter is packed in and volume how much space something takes up.

The first one: I take two balloons and blow them up to about the same size. I hang them on two ends of a ruler and pop one. Then the ruler moves like a balance and we begin talking about how air takes up space and how much mass is in the full and empty balloon.

The second one:
material: pan balances, corn flakes, raisins, plastic cups

We fill a cup with corn flakes, one with raisins, and one with a mixture. We talk about how they are all same volume because each cup is a 7 oz. cup. Then we compare their masses in a pan balance. This has always seemed to help them understand the difference.

Good luck with it.

Two other ideas are:

1) put down tape on the floor in the shape of a square, about 3 feet by three feet. Explain that you are not going to move the tape, so the size/volume of the square isn't going to change. Have two students step inside the square. Ask the class how dense the matter inside the square is. Then have more students join the square. Even though the size of the square hasn't changed, more matter has been packed in. (Do this until no more students can fit into the square. This also works well in explaining the difference between solids, liquids, and gasses. The kids in the square represent molecules.)

2) Bring a ping pong ball and a golf ball to class. They are very close in volume, but they are far different in mass. You could do this right after the above activity and ask the class why the golf ball's mass is so much greater than the ping pong ball, even though they're the same size. They should be able to tell you that the golf ball has more matter packed into it.

<<It is similar to weight, except mass is a constant. It will not change because of other variables. Weight can change with other variables introduced. For instance my mass would be the same on Earth and on the moon. My weight would change from Earth to the moon because of the lack of gravity on the moon.>>

I would suggest that mass and weight are not similar, but RELATED (weight--another name for the force of gravity--depends on the mass of two objects, usually Earth and a second object like a student or rock). To say they are similar may suggest to students that they are almost the same and that any differentiation is merely semantics the whim of a teacher of scientist. This, I think, is very different than saying they are related, which helps students to recognize that both very different and important concepts.

Secondly, in your last statement did you mean the RELATIVE lack of gravitational force on the Moon? Many young students assume there is NO gravity on the Moon, and we should be careful to avoid language that may reinforce that misconception.

I don't want to sound too picky, but the language we use about such fundamental ideas is very important. We should work toward developing a language that stresses the importance of being clear about what words mean.