Astronomy charts
Both sheets here exist because the numbers are hard to feel. The solar system chart puts size, distance from the Sun, the length of a year and the length of a day on one page, so that Jupiter's ten-hour day stops being trivia and becomes a comparison you can make with your eye.
The Moon sheet takes the eight phases through one full cycle — 29.53 days, not the 28 that gets repeated everywhere — and shows how much of the disc is lit at each of them.
Both work on a child's wall, and neither is only for children. A3 suits them: the planets need the width, and the phases want to be read from the doorway.
CONSTELLATIONS BY SEASON
the northern evening sky through the year: 28 constellations per the Yale Bright Star Catalogue, latitude 40° N, evenings near 9 pm
METEOR SHOWERS
the twelve principal showers of the year · periods, peaks and ZHR per the IMO calendar
PHASES OF THE MOON
eight phases · a full cycle of 29.53 days
MARS
size, distances and time — computed from rotation, orbit and mass
THE SOLAR SYSTEM
eight planets · size, distance, year and day
SPRING AND NEAP TIDES
the Earth–moon–sun geometry that makes the tides swing — after NOAA