Sand Dollar Inquiry

On our science/discovery table we have a variety of objects from the natural world. Students were curious about the sand dollars. One student wrote a wonder and we decided to see what the class thought about her wonder. 

The original wonder by A.B. was: I wonder why there is a hole in the shell

We then passed the sand dollar around the circle so they could each touch it and see the hole in it. We gave them think time to wonder about why there might be a hole in the sand dollar. These were their ideas...

       

P.D: because it is a little shell and it’s little

A.M: I think the hole is from the animal and it was a baby and it hatched from it 

: because one person poked a hole in it and put something in it to make sound (she had been shaking the sand dollar and heard a noise)

E.M: maybe the baby hatched out of the shell and turned to a big brother when it ate lots of food

K.B: because I wonder if it was a hole, it would look like a seed shape

D.R: a crab poked the hole

: because it’s tiny and it crashed 

V.A: forgot her idea

D.K: maybe a car drived over it and the piece fell off and then people brought it to school

We then found some information online about what a sand dollar was. We looked at pictures of the alive ones and realized that ours wasn’t alive anymore. 

                        

Ms. Tompkins: what is different between our sand dollar and the one in this picture?

: it came from water and the water pushed it back

K.B: it’s hard, it’s white and when it’s soft it’s purple and kind of pink

T.K: it’s purple and it’s a circle

P.D:  it’s soft and purple and when it’s died it looks smaller

E.M: the shape inside is kind of a star

N.M: I wonder

D.K: when it was purple it used to alive, now it’s white and dead

A.M: we should put it in the water


We watched a video of a sand dollar moving through the sand (Click below to watch). We learned that sand dollars can only been seen moving if you speed up the film. This is because they are one of the slowest moving species on earth! When we paused the video after the sand dollar buried himself in the sand, the students had some wonders...

Video: The Sand Dollar- YouTube

K.B: he’s going to get sand in his mouth!

Ms. Tompkins: what do you all think about that?

P.D: maybe he closes his mouth and then he buries in sand and then he helps himself get into the sand

: he is trying to get alive again

D.R: where is his mouth?

A.B: in the tiny hole on the bottom 

A.M said we should put the sand dollar into water and a few other kids agreed and said we should add sand as well. Ms. Tompkins put water and sand into a clear container and then we added two of our sand dollars.

Ms. Tompkins: what do you think is going to happen?

A.M: its going to turn purple

A.B: I think it will walk

K.B: it’s going to grow legs. I see a line of dead legs

T.K: it’s going to turn purple and black

: I think it is going to turn alive

D.S: is going to come here

: I think it’s going to bury itself

: it may get real again

M.P: going to go purple

A.M: maybe add more water and sand to make it alive

K.B: (looking at the star) around it are the petals and in the middle is the star 

Ms. Tompkins: what do you think they are for?

K.B: I don’t know, maybe they are for it to keep warm

Students were touching the sand dollars in the bin with the water and then touching the sand dollar that was still sitting on the table.

Ms. Tompkins: how does it feel?

T.K: it feels hard, so hard

K.B: it feels like wet sand. 

Ms. Tompkins: do they feel different?

K.B: that one is wet (pointed to the one in the box), that one is dry (pointed to the one on the table)

D.R: is it alive?

Ms. Tompkins: do you think it will come alive or stay non-living?

D.R: I think not alive because it is already frozen 

Before lunch we had a class meeting to look at our sand dollars again. 

Ms. Tompkins: Has anything changed? 

Class: “No!”

Ms. Tompkins: Do you think it will come back alive?

D.K: when people are died then they see Jesus, so maybe it is the same for animals

D.R: maybe someone freezed them so they won’t be alive

A.M: maybe they need the sunlight to be alive

: they need more sand

T.K: they need more water

The students decided we needed to leave the sand dollars in this bucket of sand and water over night to see what would happen the next morning.


T.K: they are different sizes, it got bigger

Ms. Tompkins pointed out that each sand dollar is a different size.

K.B: maybe they are different sizes because they are from different countries

P.D: they must be small and big and they can’t move because they aren’t purple and don’t have legs and can’t walk

: someone chopped the legs

We watched a different movie of a sand dollar moving on the sand in circles. (Click below to watch)

Video: Time Lapse of a Sand Dollar- YouTube

Ms. Tompkins: Does anyone have anymore wonders about sand dollars?

K.B: where are his eyes? I wonder if it eats sand or crumbs

V.A: I wonder where are his legs

A.M: we can ask to put it back where it belongs

A.B: I wonder why it’s kind of dark purple

: I wonder where is its nose

A.K: I wonder sand dollars

S.C: I wonder what the noise in the sand dollar is

P.D: I wonder why it moves so slow and where does it live?

D.S: I wonder can he go faster with help and put him in the water

: I wonder why it moves so slow

D.Z: I wonder if it eats fruits

E.M: does sand dollar actually live in sand

M.P: I wonder why it’s purple

Z.H: I wonder about when it’s moving

: I wonder if it has a nose

: I wonder why you have to have it in water

The students had a lot of enthusiasm about sand dollars and were excited to share their thoughts and wonders about them. We also were excited about these wonders because we had the same ones ourselves! We were learning right alongside the students. 
Stay tuned to see what else we learn about sand dollars!

Ask your child if they have any more wonders about sand dollars.