Gather:

    * 16 Milk cartons, plastic bottles or other similar containers

    *  Potting soil

    *  Water

    *  Large bean seeds

    * 4 cardboard boxes big enough to cover the containers and keep out light

    * 4 plastic bags, such as gallon size

    * String

    *  Scissors

    *  Paper and pencil

    *  Ruler

    *  Permanent pen such as a Sharpie

Explore:

Think about what conditions plants need in order to grow.

Here is a design for an experiment to test some of your ideas. Cut off the tops of the milk cartons or plastic bottles with scissors. Poke a few drain holes in the bottom of each container with the scissors. Ask an adult to help. Label each container with the permanent marker so you can remember which treatment it is. Label four containers with the word "control." Label four containers "no light." These containers will be placed under the cardboard boxes. Label four containers "no air." These containers will be covered with the plastic bags tied with string to keep air out. Label four containers "no water." These containers will not be watered.

Fill the cartons with the soil. Plant the seeds in exactly the same way in each container. Water the twelve containers you have chosen to receive water. Cover the ones that are to be dark, wrap in plastic those that are not going to get fresh air. Check every other day to add water as necessary and record your results by measuring the height of each plant. Which plants grew best? What conditions do plants need for proper growth?

Can you think of any other variables to test? What about hot versus cold temperatures? What about giving some plants fertilizer and other none? Carry out your experiment and record the results.