science experiments ideas

Place a pair of binoculars in an open window in the direct path of the suns rays. Stand a mirror in front of one eyepiece so that it throws an image of the sun on to the opposite wall of the room. Adjust the mirror until the image is sharp, and darken the room.
You would risk damaging your eyes if you looked directly at the sun through binoculars, but you can view the bright disc on the wall as large and clear as in the movies. Clouds and birds passing over can also be distinguished and. if the binoculars are good even sunspots. These are a few hot areas on the glowing sphere, some so big that many terrestrial globes could fit into them. Because of the earths rotation, the suns image moves quite quickly across the wall. Do not forget to re align the binoculars from time to time onto the sun. The moon and stars cannot be observed in this way because the light coming from them is too weak.

Place a flowerpot with a long stick fixed into the hole at the bottom in a spot, which is sunny, all day. The sticks shadow moves along the rim of the pot as the sun moves. Each hour by the clock mark the position of the shadow on the pot. If the sun is shining, you can read off the time. Because of the rotation of the earth the sun apparently passes over us in a semi circle. In the morning and evening its shadow strikes the pot superficially, while; it midday, around 12 oclock, the light incidence is greatest. The shadow can be seen particularly clearly on the sloping wall of the pot.

Hold a watch horizontally, with the hour hand pointing directly to the sun. If you halve the distance between the hour hand and the 12 with a match, the end of the match points directly to the south. In 24 hours the sun

The earth rotates in 24 hours from west to east once on its axis. In this time the sun shines on all regions of the globe one after the other and determines their time of day. To enable a practical calculation of the time, the earth is divided into 24 time zones, which are very simply shown on the map below. Since in a few areas, which belong together, a uniform time has been introduced, the boundaries of the time zones sometimes run along state boundaries. For example, Mexico has Central time. The West European countries including Great Britain has together with the Middle European countries, Middle European time.
According to the map, when it is 13.00 hours there it is only 7 oclock in the morning on the East Coast of the U.S.A. in Japan it is already 21 .00 hours and on the right edge dateline a new day is beginning. The time zones are shown on the world time disk pictured below. Copy or stick this onto a piece of cardboard and cut it out. Colour the panel corresponding to time zone were you live red. Remove the casing and glass from an alarm clock, push the minute hand through the hole in the paper disk and fix it firmly to the hour hand. Make sure that the red coloured panel is exactly over the hour hand. If you rotate the disk with this, it should not stick. The clock will tell you all time of the day on the earth.
Read off first on the red panel the time of the place where you live. If you rotate the disk to the left, you will find the time zones of places west of you. In each panel, the time is an hour earlier. If you rotate to the right, you will find the places east of you. In each panel the time is an hour later. The outer circle continues into the inner circle at the crossed arrows and vice versa. For example in New York it is 6.15 in the morning. Then it is already 20.15 in Tokyo and in New Zealand a new day will begin in 45 minutes. Or in London it is 20.03. What time is it in San Francisco? Look at the world map San Francisco lies in the time zone of Los Angeles. On the rotating disk go to the left to the Los Angeles panel. The time is 11.03.

Plant a sprouting potato in moist soil in a pot. Place it in the corner of a shoebox and cut a hole in the opposite side. Inside stick two partitions, so that a small gap is left. Close the box and place it in a window. After a couple of days the shoot has found its way through the dark maze to the light.
Plants have light sensitive cells, which guide the direction of growth. Even the minimum amount of light entering the box causes the shoot to bend. It looks quite white, because the important green colouring material, chlorophyll, necessary for healthy growth, cannot be formed in the dark.

Fill a large glass jar with fresh water and place in it several shoots of water weed.
Place the jar in sunlight, and at once small gas bubbles will rise in the water. Invert a funnel over the plants and over it a water filled glass tube. The gas, which is given off by the plants slowly, fills the tube.
Plants use sunlight. With its help, in the presence of chlorophyll, they make their building material, starch, from water and carbon dioxide, and give off oxygen. Oxygen has actually collected in the glass tube. If you remove the tube and hold a glowing splint in it, the splint will burn brightly.

Fill a bottle with water and place it upside down and half buried in soil in a flower box. An air bubble rises up in the bottle from time to time, showing that the plants are using the water. The water reservoir is enough for several days, depending on the number of plants and the weather. Water only flows from the bottle until the soil round it is soaked. It starts to flow again only when the plants have drawn so much water from the soil that it becomes dry, and air can enter the bottle. One notices that plants can take water more easily from loose soil than from hard.

Dissolve a teaspoonful of salt in a glass of water and cover it tightly with parchment paper. Place the glass upside down in a dish containing water strongly coloured with vegetable dye. Although the parchment paper has no visible holes; the water in the glass is soon evenly coloured. The tiny particles of water and dye pass through the invisible pores in the parchment paper. We call such an exchange of liquids through a permeable membrane, osmosis.

Make a deep hole in a carrot and fill it with water in which you have dissolved plenty of sugar. Close the opening firmly with a bored cork, and push a plastic straw through the hole. Mop up any overflowing sugar solution, and seal the joints with melted candle wax. Put the carrot into water and watch after some time the sugar solution rises into the straw.
The water particles can enter the carrot through the cell walls, but the larger sugar particles cannot come out. The sugar solution becomes diluted and rises up the tube. This experiment on osmosis illustrates how plants absorb water from the soil and carry it upwards.

Fill a wineglass to overflowing with dried peas, pour in water up to the brim, and place the glass on a metal lid. The pea heap becomes slowly higher and then a clatter of falling peas begins, which goes on for hours.
This is again an osmotic process. Water penetrates into the pea cells through the skin and dissolves the nutrients in them. The pressure thus formed makes the peas swell. In the same way the water necessary for life penetrates the walls of all plant cells, stretching them. If the plant obtains no more water, its cells become flabby and it wilts.