Ahead of time, chill the isopropyl alcohol in the freezer or in an ice water bath.
1. Place several strawberries into a plastic Ziploc bag. It is not necessary to remove the stems. Add about 1 teaspoon of water per strawberry, enough to make it slightly liquid but not so much that the solution will be diluted too much. Close the bag and crush the strawberries thoroughly, until there are no lumps.
2. Filter through a coffee filter or a double layer of cheesecloth and collect the liquid in a test tube or clear plastic cup. Cheesecloth works faster; filtering through a coffee filter can be very slow.
3. Add 1/4 teaspoon of table salt for each tablespoon of juice collected and stir with the popsicle stick or wooden skewer to dissolve the salt.
4. Add about 1 teaspoon of dishwashing detergent, liquid hand soap or shampoo for each tablespoon of strawberry juice. Stir well until thoroughly mixed, but avoid making bubbles. Let it sit for about 5 minutes.
5. Tilt the test tube or cup and carefully pour the ice cold isopropyl alcohol down the side. Alcohol is less dense than water, and it will form a clear layer on top. After a few minutes, white strands or clumps of DNA should begin to appear in the alcohol layer.