Ideas For 3rd Grade



1. Mushroom Prints.

The best time for this experiment is late summer - early autumn, when there are many kinds of mushrooms are ready to be collected in the nearest forest.

Goal: collect mushroom prints from different kinds of mushrooms

Procedure:

  • Cut the cap off the mushroom, close to the mushroom gills.
  • Put the cap on the clean piece of paper (gills down to the paper).
  • If you know the name of the mushroom, write it on the paper somewhere in the corner.
  • Mushroom gills produce tiny spores that can be carried away with subtle wind. To make a better print, cover each cap with the glass. Let it stay for 24 hours.
  • Carefully remove the glass and the cap. You will see "negative" print of the gills on the paper. Color of the print will depend on the species of mushroom.
  • Pores will attach to the paper quite well but to fix them for a long term storage you can spray them with a hair spray from the distance 40-50 cm (~1.5 feet). Wait a few minutes until the spray completely dries and your mushroom print is ready for presentation.

You can study collected spores under a microscope. You can also try to collect a lot of spores, put them in special substrate and try to grow your own mushrooms, but you should know that only few species of mushrooms were successfully grown artificially. For some reason mushrooms are very picky to their environment and prefer to grow in the wild.

In food industry they use this method of spore extraction to isolate and check certain strains of commercially available mushrooms.



2. Camera Obscura.

This science project has its roots way back in history. This effect was first noticed by ancient Greeks, who observed it but could not explain it. Many centuries later this effect was investigated by great Muslim mathematician and astronomer Ibn Al Hatam. He acclaimed as the first man who did science using experiments to prove the theory (hence he was the first man who used modern scientific method).

Goal: Build pinhole camera, observe how it works.

For this third grade science presentation you'll need:

  • Small (5-15 cm) cardboard box or box made of black plastic.
  • Needle.
  • Aluminum foil.
  • Piece of baking paper or frosted glass.
  • Dark room.
  • Torch.
  • Small lens (optional).

Procedure:

  • Cut a small circular hole in the center of one of the cardboard box's walls. This will be pinhole wall. Cut bigger square hole in the opposite wall. Glue piece of baking paper or tape frosted glass in place of this wall. This wall will be your image plane wall.
  • Glue the piece of foil to the pinhole side of the box in covering the circular hole. Carefully make a pinhole in the foil using the needle. Make sure the hole is small and round. (You can make the hole first and then glue the foil to the box).
  • Check your pinhole camera (or camera obscura) in the dark room. If you put some brightly lit object in front of the camera (that's where you need a torch) you should see it's dim image on the baking paper/frost glass.

Try answering following questions:

  • Is this image sharp?
  • Is it sharper if the bright object further closer to the box?
  • What's strange about this image?
  • What happens if you make 2 pinholes in the aluminum foil close to each other?
  • What happens if you make pinhole of bigger size?
  • What happens if instead of the aluminum foil you put a lens on the front side of the box?

Note: Because the pinhole is so small and lets only a tiny amount of light in the camera, the image on the image plane wall will be very dim. You will see it only in the dark room and only if camera is pointing at well illuminated objects. If you have a room with dark curtains you can darken it during the day and point the camera outside. It may or may not work. Other things to watch: white flower illuminated by bright light from a short distance. Lightbulb. Candle flame will work too (make sure you do this part under adult supervision!). Another great object for pinhole camera is our Sun.



3. Simple Mold Garden

The goal of this 3rd grade science project is to find out how many different species of mold live in our home.

You'll need:

  • Few small plastic containers or one big container with lids.
  • Tea.
  • Jar with lid.
  • Bread.
  • One or two different fruits.
  • Water spray.

Procedure :

  • Put a slice of bread and fruits in the individual containers or one big container.
  • Spray them with water and leave the containers open for a couple of hours.
  • Put some tea leaves in the jar and fill with hot water.
  • Let the tea cool down and leave it open for hour or two after that.
  • Cover the jar and containers with the lids and put them in a dark warm place.
  • Check them every day.

Results: In a few days depending on the temperature and number of other conditions you'll notice mold growing. Depending on the species it may form circular colonies or fluffy mass that may fill a lot of space. Day or two after you 'll notice the first mold started produce spores. They will be visible usually at the center of the colony and may be of different colors depending on the species.

Note:

  • Do not open container lid if you can see through.
  • If you opened it do not touch the mold!
  • Try not to breathe in the spores they may cause allergy and even infection! Hold your breath if you opened lid and looking at mold closely.
  • Try count individual colonies and draw them.
  • Colonies floating in the water surface of the tea jar may look very beautiful Try to take photos of them.
  • Try to identify mold species.
  • Dispose containers after you're done with this experiment!



4. Brine Shrimp Development.

Brine shrimps are available in the pet shops or you can order them online. Brine shrimps live in salty inland waters (but not in the sea). They can be used as a model animals in science fair experiments regarding water quality and contamination.

The goal of this project: study brineshrimp development and anatomy.

You'll need:

  • Brine shrimp eggs
  • Jars
  • Rock salt
  • Fresh water
  • Yeasts
  • Zoom lens or a microscope.

Procedure:

  • Fill the jars with tap water and let it stay for a few days to clear off chlorine.
  • Dissolve 1.5 tablespoon of rock salt in quart of water (brine shrimps can live in the range of different salinities so you should not be very accurate).
  • Put brine shrimp eggs in the water and leave them for 24 hours at temperature ~20-25 C.Put brine shrimp eggs in the water and leave them for 24 hours at temperature ~20-25 C.
  • In 24-48 hours you'll see that some of eggs have white embryos attached to them. Few hours later you'll see a first baby brine shrimp (called nauplii) free floating in water.
  • Feed them with a small amount of yeasts and/or boiled egg yolk or flour.

Check more detailed information on growing brine shrimp.When eggs hatched you can observe nauplii growing from this stage


 

To this stage:



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