LOWKEY SMART

Say the times table facts out loud: speed comes from saying them often.

A flowering plant has roots, a stem, leaves and flowers. The roots hold the plant firmly in the soil and take in water and minerals (nutrients) from it. The stem holds the plant up and carries water from the roots to the leaves and flowers. The leaves use sunlight, air and water to make food for the plant. The flowers make seeds so that new plants can grow. To grow well, most plants need light, water, air, nutrients from the soil, space and the right temperature.

Rocks are natural solids found in the ground. Granite is a very hard rock that does not let water through. Chalk and sandstone are softer rocks that let water soak in, and chalk crumbles easily. A rock that lets water soak in is called permeable; a rock that does not is called impermeable. Fossils are the remains or shapes of living things from long ago, preserved in rock. Soil is made of tiny bits of rock mixed with rotting plants and animals (called organic matter), air and water.

We need light to see things. Light comes from light sources such as the Sun, a torch or a candle. Dark is the absence of light, which means there is no light. The Moon is not a light source: it reflects light from the Sun. Light travels in straight lines. Some surfaces reflect light, which means they bounce it back; smooth, shiny surfaces such as mirrors reflect light well. A shadow forms when an opaque object blocks the light. Moving the object closer to the light source makes its shadow bigger. Never look straight at the Sun, because its light can damage your eyes.

A force is a push or a pull. Friction is a force that slows things down when two surfaces rub together. Moving things slow down faster on rough surfaces, such as carpet, than on smooth surfaces, such as ice. Magnets can pull (attract) some metals, such as iron and steel, without even touching them. Every magnet has two ends called poles: a north pole and a south pole. Two like poles, such as north and north, push apart; this is called repelling. A north pole and a south pole attract each other.

Plants make their own food, but animals, including humans, cannot, so they must eat to get nutrition. A balanced diet has the right amounts of different food groups. Carbohydrates, such as bread, rice and pasta, give us energy. Proteins, such as meat, fish, eggs and beans, help the body grow and repair itself. Fruit and vegetables give us vitamins and minerals, which keep us healthy. Dairy foods, such as milk and cheese, contain calcium for strong bones and teeth. Fats give energy too, but we should only eat small amounts of them.

Humans and many other animals have a skeleton made of bones inside their bodies. The skeleton supports the body, protects organs and helps us move. The skull protects the brain, and the ribs protect the heart and lungs. Muscles are attached to bones: when a muscle contracts (gets shorter) it pulls on the bone and makes it move. Joints, such as the knee and the elbow, are where bones meet so the body can bend. Insects have a hard outer covering called an exoskeleton instead. Worms and slugs have no skeleton at all.