Classroom

You need something for tomorrow's lesson: an activity to hand out, a way to show why the Moon changes shape, a link thirty students can open without signing up. Classroom gathers eleven free tools for those jobs, from bingo cards dealt one per student to a Moon calendar for your own town. None of them asks for an account, yours or your students'.

Printables, and a sudoku the class plays on screen

The bingo card generator deals the lines you type, from 24 up to 60, into 5×5 cards with a free centre, and past 24 lines each card draws a different set. The Back to school preset gives you a first list to edit. The QR code generator puts a link on paper, as a single code or a sheet of up to 48 to cut out.

The sudoku solver and generator is played in the page, and today's grid is the same for everyone who opens it that day. Its hint names the deduction behind a cell, such as a hidden single or a pointing pair, so a stuck student learns the move instead of being handed the digit.

Science lessons computed for your own town

The Moon phase calendar gives your city's month night by night: the phase and its name, the share of the disc lit, moonrise and moonset. A first quarter rises around midday, so students can find it in the afternoon sky. The equinox and solstice dates give the four instants of the year and, for your city, its longest and shortest days. The Earth is nearest the Sun in early January, a line I would show before any diagram of the tilt, since it rules distance out.

What colour is the sky names the light over any city from the Sun's height: golden hour, blue hour, twilight, night.

Coordinates and clocks start from a place name

The latitude and longitude finder turns a city into coordinates, with its country and time zone, and gives the antipode, the point on the exact other side of the Earth. What time is it in any city reads the clock anywhere, with the UTC offset and daylight saving. India at +5:30 and Nepal at +5:45 show a class that offsets are political rather than geometric.

Class life, from the countdown to the quote of the week

The countdown card maker counts the days to the last day of school, one of the headlines it suggests. The form generator starts from an errand, such as Your feedback for a class poll, and hands back the link to a working form; whoever answers needs no account, and the answers go where you choose, your own mail app included. The quote card maker sets the quote of the week as an image, with its author.

Each tool hands back a file or a link

• Bingo: a PDF with one card per student, up to 30, and a draw sheet.
• QR codes: a PNG, or an SVG that prints at any size.
• Countdown: an image, or an embed that recounts on every page load.
• Form: its address, which is the form itself; nothing is stored on the site.

The sudoku is the exception: it keeps no history, and a reload clears the grid.

Questions

Are these free tools for teachers?

Yes, all eleven, with no account for you or your students.

Which sudoku size suits younger students?

The 6×6, digits 1 to 6, which the tool gives as the size for children; on easy, a drawn grid keeps the most clues.