Designing housing
Think about what the animal needs: space (not crowded), air (small holes or a net lid), safe walls that it cannot escape through and pests cannot enter, light (indirect, not a hot window) and an easy way to clean it.
- Silkworm box: a shallow cardboard or plastic tray with a net or paper lid with small holes, a clean cloth or paper floor, and twigs for later spinning.
- Fish tank: a clear tank or large jar with clean, de-chlorinated water, a few water plants, a lid with air holes, and light but not direct sun.
Draw your design first and list the materials. Wash your hands after handling animals.
Controlling conditions
Four conditions matter: temperature, food, cleanliness and air or oxygen.
- Temperature: silkworm larvae grow well at about 23–28 °C; many tropical fish like about 24–28 °C. Use a thermometer. In winter, keep the box in a warm room; in summer, keep it shaded.
- Food: fresh, clean mulberry leaves for silkworms (not wet, not old); small amounts of fish food once or twice a day for fish. Remove leftovers.
- Cleanliness: remove waste daily; change part of the fish water regularly.
- Air: never seal the box. Fish need dissolved oxygen, so do not overcrowd them.
Recording growth
Measure on the same days each week (or every day). For a silkworm, record length in mm; for a fish, length and number alive. Use a table: day, length, food given, temperature, notes. Draw a line graph or bar chart of length against day.
A healthy animal grows steadily. A flat line means a problem: too cold, too little food, dirty box or disease. Change one condition and watch what happens.
Care for the animal: handle gently, never harm it for the project, and release fish or return worms to a proper place when you are done, as your teacher advises.
Life cycle link
The silkworm shows a full life cycle: egg, larva (the worm that eats and grows), pupa (inside a cocoon) and moth. Record which stage it reaches and how many days each takes.
Key formulas and definitions
- Plan: Home – Air – Temperature – Food – Record
- Best temperature for silkworms is about 25 °C
- Growth rate = change in length ÷ number of days
- Change only one condition at a time
Worked examples
1. A worm is 5 mm on day 1 and 25 mm on day 11. Find its average growth per day.
(25 − 5) ÷ (11 − 1) = 20 ÷ 10 = 2 mm per day.
2. A box has no air holes. The worms become weak. Why?
They cannot get fresh air (oxygen), and heat and moisture build up. Add small air holes covered with net.
3. A student keeps the box at 12 °C and growth is very slow. What is the likely cause and fix?
It is too cold. Move the box to a warmer room near 25 °C.
4. Leftover leaves rot in the box. What should you do?
Remove leftovers daily and give fresh leaves in smaller amounts, so mould and germs do not spread.
5. Why record growth in a table and graph?
A table keeps the numbers safe, and a graph shows the pattern, such as a flat line that signals a problem.
Common mistakes
- Sealing the box with no air holes.
- Placing the box in hot direct sun or a cold corner.
- Overfeeding and leaving rotten food in the box.
- Changing temperature, food and light all at once, so you cannot find the cause.