These sand timers are a great project for your classroom, or on the weekend. We use these timers at our elementary school to set a limit for different materials. You can make a timer range from 4 minutes to about 10 minutes, depending on the size of your bottles.
This is a great way to talk about recycling, and also to practice math skills! We had to figure out the rate at which the sand would flow, and then approximately how much sand would be needed for the amount of time we desired. Let us see your sand timers or any additions you have!
Created by students at Redwood Coast Montessori School.
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Step 1: Gather Supplies
2 plastic bottles of the same size, must be from carbonated beverages
Dry, sifted sand about 20 ounces volume
Hot Glue Gun
Drill and 3/16” drill bit
Step 2: Clean Out and Dry Soda Bottles
Get two carbonated soda bottles that are the same size. **Must be carbonated beverage bottles, these use a stronger type of plastic that we need for this large weight.***
Make sure to clean out completely with soap and water, you will need to get out all of the stickiness and gunk left behind. This step takes awhile, as you need to let the bottles dry out naturally in the sun. We like to be cautious and let ours dry for a complete 24 hours before proceeding.
Step 3: Collect and Dry Sand
Go to a local beach where it is legal to harvest sand from the beach. For a ten minute timer, you will need to collect approximately 20 ounces of dry sand.
If you do not have access to a beach or another place with sand you can purchase some from your local pet store.
Then get a large pan and dry out the sand in the oven or in the sun. Make sure the sand is completely dry before proceeding to next steps. Otherwise the wet sand may clump up, and the timer will not work.
Just like cleaning out the bottles, we were extra safe and let our sand dry out for a complete 24 hours before proceeding.
Step 4: Sift Your Sand
You must sift the sand at least twice because there can be little debris in it that may block the hole. When in doubt, sift it again! We found that we had to sift our sand about 4 times before it flowed perfectly.
Step 5: Hot Glue Lids and Drill Hole
Use a generous amount of hot glue, and press firmly so the lids are connected. We like to use a bit of duct tape to reinforce this seal, as well as to make it look the same color and more uniform.
Use a 3/16" drill bit, with proper supervision and safety equipment. As close as possible to the center, drill your hole. Try to scrape off any bits of plastic that may cause a blockage in the timer.
Step 6: Add Approximate Amount of Sand and Test
You should now essentially have a functioning sand timer.
Now for the fun part! Use your funnel and measuring cup to add the sand in. We have found that for each 10 ounce of sand, you will have approximately 5 minutes of time. This is with Humboldt County Sand, so your variety may flow a bit faster or slower. We feel that this is a good place to start. Use a digital clock to test your timer, and take or add any amount you may need to suit your needs.
Great work Upcycler! Spread the word! Upcycle More!