17 experiments found
Clear filtersA microscope's magnification is the eyepiece's magnification times the objective's; the more it magnifies, the bigger and fewer the cells we see
Look at onion skin cells and cheek cells through a school microscope. Turn to stronger lenses and find out how magnification changes what you see.
Living things are classified into five kingdoms by their cells (one or many, with or without a nucleus) and how they get their food
Look at the cells of fifteen living things, from curd bacteria and amoeba to yarsagumba, rhododendron and frogs, find out how each gets its food, and sort them into the five kingdoms.
South Asian farmers grow kharif crops in the monsoon, rabi crops in the winter and zaid crops in the short summer between, because each crop needs its own temperature and water
Find out when twelve crops of India, Bangladesh and Nepal are sown and harvested, from paddy and jute to wheat, mustard and watermelon, and sort them into kharif, rabi and zaid crops.
Roots absorb water mainly through their root hairs, by osmosis; salty water stops absorption
Stand young plants in measuring cylinders of water sealed with oil, compare intact roots, damaged root hairs and cut-off roots, and try salty water.
Oviparous animals lay eggs and viviparous animals give birth to young; fertilisation happens inside the female (internal) or outside in water (external)
Find out how twelve animals, from the hen and the frog to the cow and the whale, have their young and where fertilisation happens, then sort them into egg-layers and those that give birth.
Pollen is carried to the stigma, a pollen tube carries the male gamete to the ovule, and after fertilisation the ovule becomes a seed and the ovary a fruit
Put the stages of pollination, fertilisation, seed and fruit formation and germination in the right order, and find out where in the flower each one happens.
A flower's stamens (anther and filament) are the male parts and its pistil (stigma, style and ovary with ovules) is the female part; petals and sepals attract and protect
Cut a flower in half, label its petals, sepals, stamens and pistil, and find out which parts are male and which are female.
Body mass index compares mass with height: BMI = mass (kg) ÷ height² (m²); for adults 18.5 to under 25 is a healthy range, but children are still growing, so their BMI is checked on charts for their age and sex
Choose a mass and a height and work out the body mass index, BMI = mass ÷ height². See which adult band it falls in, and learn why doctors use age charts, not these bands, for growing children.
Energy used (kcal) ≈ MET × body mass (kg) × time (hours), where the MET says how many times harder than resting an activity is; harder play, a heavier body and longer play all use more energy
Choose a game or exercise, your body mass and how long you play, and work out how much food energy your body uses, in kilocalories and in rotis.
First aid is the help given before a doctor arrives: it keeps the person safe, stops things getting worse and gets them to proper care; some common habits, like ice on burns or sucking snake venom, harm or waste precious time
Twelve things people do for burns, cuts, nosebleeds, snake and dog bites, diarrhoea and someone who has fainted. Find out why each helps or harms, and sort the good first aid from the old habits that do damage.
Each case of a disease infects R₀ people when no one is immune; when more than 1 − 1/R₀ of people are vaccinated, each case infects fewer than one other and the disease dies out, protecting even those who cannot be vaccinated
Choose a disease, from flu to measles, and how many people in a town are vaccinated. See how many people each case infects now, how many must be vaccinated for herd immunity, and whether the disease dies out or keeps spreading.
Bacteria multiply by splitting in two; in warm food they can double every 20 minutes, so after n doublings one germ becomes 2ⁿ, which grows faster and faster
Start with one germ on a plate of food left out in the warm. Choose how often it doubles and how many hours pass, and watch one germ become thousands, then millions, which is why cooked food should not sit out for long.
The body loses water in sweat, breath and urine, so a child needs about 35 mL of water for every kg of body mass each day, more when playing hard and on hot days
Choose a body mass, the minutes of hard play and whether it is a hot day, and work out how much water a child needs in a day, in millilitres and in glasses.
Inherited traits are set by genes passed from parents to children; acquired traits are learnt or gained during life, from practice, injury or the surroundings, and are not passed on in the genes
Look at twelve traits, from eye colour and dimples to a scar, a suntan and the language you speak. Find where each comes from and whether your children could get it from you, then sort them into inherited and acquired traits.
A lack of one nutrient causes a deficiency disease: vitamin A night blindness, vitamin C scurvy, vitamin D rickets, vitamin B1 beriberi, iron anaemia and iodine goitre; foods rich in that nutrient prevent it
Twelve cards show a sign of poor diet, such as night blindness or a swollen neck, or a food that prevents one, such as carrots or iodised salt. Find out what each tells you, then sort them by the vitamin or mineral they are about.
Red cells may carry A, B and Rh antigens; a patient's blood attacks any A or B it lacks, and an Rh-negative patient reacts to Rh, so O− can give to everyone and AB+ can take from everyone
Check twelve donor and patient pairs, from O− to A+ and AB+ to O−. Find the antigens on the donor's red cells and the antibodies in the patient's blood, and sort each transfusion as safe or not safe.
Plants cannot move, so they spread their seeds away from the parent plant by wind, water, animals or bursting pods, and each seed or fruit has a shape that suits its way of travelling
Look closely at twelve seeds and fruits, from the dandelion's parachute to the coconut's husk and the burr's hooks, and sort them by how they travel: by wind, by water, by animals or by bursting pods.