There are TONS of slime recipes online. Some great and some not so great. During our summer school program I decided to have some of my kids experiment with different types of slime recipes and ingredients. They all started with a base recipe and then changed it as they tried different things. This recipe is one we came up with for magnetic slime.
Step 1: BoM
Food coloring (optional)
Step 2: Glue
Mix 4-6oz of glue with 1/2 cup of warm water. If you want color, this is the time to add it.
Step 3: Borax
Mix 1 tsp of Borax with 1 cup of warm water.
Step 4: Mix
Slowly pour the Borax water into the glue cup and mix as much as you can. Remove the clumpy mixture from the cup and knead with your hands.
Step 5: Iron Oxide
When the slime has been kneaded a bit, add the iron oxide (start with a tablespoon) to your slime and knead it
Step 6: Test!
Using magnets (the more powerful the better) test your slime! We have weak magnetics so we were not able to get the slime to move on its own, but the magnets did stick to the slime, which was pretty cool.