Perpetual Calendar a paper tech printable lesson ) 1 Cut out all of the components along the dotted lines. In the center of each piece, punch a hole where indicated. You can use a hole punch, an x-acto knife (be careful!) or a any sharp, pointy object. is a Planetarium This Book 2 Books and Chronicle @kellianderson HP, by you to brought from (pop-up adapted Use a brad through the center of both holes to create a spindle. If you don’t have a brad, try threading a doubled-up twist-tie through the holes and then bending it into an I=beam shape 3 print-at-home calendar perpetual Now, the wheel should turn freely underneath the top layer. Ta-da, you just made a paper-engineering mechanism called a volvelle. Perpetual Calendar HO LE 1 8 15 2 22 9 29 3 1 7 6 10 4 5 6 23 14 17 11 12 13 30 21 24 18 19 20 28 3 25 1 26 27 CUT LINE Top Layer 2034 2033 2032 2038 2054 2016 2031 2030 2018 HO LE 2029 2019 2028 2042 2050 2020 2027 2021 2026 2022 2025 2023 2024 2046 1 2 To determine the date for After the year 2043, any day between now and you can reuse the old 2043, turn the wheel to years; 2044 maps to display the year in question 2015 again, 2045 to within the window for the 2016, and so on. month in question. The month’s numerical dates now each correctly correlate with the days of the week on which they fall. Wheel Layer a paper tech printable lesson ) Why it works Calendars are humans’ attempt to make the observable passage of time (daylight cycles and seasonal cycles) predictable. The unit-based system of days and years assigned to the cycles are specific, yet imprecise. This is is a Planetarium This Book because the earth’s rotation on its axis is not syncopated with the speed in which the earth orbits the sun. As a result, an Earth year is not actually 365 days long—it is exactly 365.242 days. The Gregorian calendar corrects for this extra fraction of a day by including a 366th day every fourth year, called a leap year, which keeps the calendar months predictably in sync with the seasons. This Books and Chronicle @kellianderson HP, by you to brought from (pop-up adapted perpetual calendar works because it is a wheel—which, like a year, is also a cycle divisible into smaller units. It contains all of the dates for 28 years and will accurately provide the date for every year from 2015 to 2043, and then can be extended beyond in perpetuity. Understanding it even more… print-at-home calendar perpetual • What day of the week will your 20th birthday fall on? • What day of the week will you celebrate turning 52? (And what do you think you’ll do that day? Want to set up a calendar event now? :) ) • When is the next Saturday birthday you'll enjoy? • Why is your birthday on a different day each year? Perpetual Calendar.