Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 425 · 40 questions

What you do (Heat shows the secret): 1. Dip a cotton bud in lemon juice and write a secret message on white paper. 2. Let the paper dry completely — the writing disappears. 3. An adult irons the paper on a low setting while you watch from a safe distance. 4. Read the brown message and wash your hands.

1. 1.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is kept the same. (a) True (b) False
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a magnet (c) a cotton bud (d) an adult with an iron
3. 3.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) wash your hands (c) lick your fingers (d) rub your eyes
4. 4.🔍 Which is the odd one out? (a) plugging in the iron (b) dipping the cotton bud (c) cutting the lemon (d) ironing the paper
5. 5.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
6. 6.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
7. 7.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
8. 8.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
9. 9.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if cooled (d) yes, if shaken
10. 10.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) a magnet (c) lemon juice (d) a mirror
11. 11.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
12. 12.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) turmeric powder (d) a small bowl
13. 13.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) dry juice is see-through (d) the paper ate it
14. 14.True or false: writing the message is a job a child can do. (a) False (b) True
15. 15.🧺 Do we need a small bowl for the secret lemon message? (a) needed (b) not needed
16. 16.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we keep it the same (b) we measure it (c) we change it
17. 17.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it is sticky (c) it is cold (d) it can burn skin
18. 18.🛟 Who should use the hot iron in the secret message experiment? (a) any child (b) the youngest child (c) whoever is fastest (d) only an adult
19. 19.🧺 Do we need a magnet for the secret lemon message? (a) not needed (b) needed
20. 20.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) cutting the lemon
21. 21.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) cutting the lemon (c) writing the message (d) plugging in the iron
22. 22.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a mirror (d) an adult with an iron
23. 23.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
24. 24.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
25. 25.🔮 Predict: the adult irons for only one second. What happens? (a) writing turns green (b) writing stays faint (c) the paper floats (d) it gets darker
26. 26.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
27. 27.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we measure it (b) we change it (c) we keep it the same
28. 28.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) letting the paper dry (d) plugging in the iron
29. 29.🍋 Which of these steps is a job for an adult? (a) reading the message (b) dipping the cotton bud (c) letting the paper dry (d) ironing the paper
30. 30.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
31. 31.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
32. 32.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
33. 33.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is what we measure. (a) False (b) True
34. 34.True or false: a small bowl is needed for the secret lemon message. (a) True (b) False
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we keep it the same (b) we change it (c) we measure it
36. 36.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) putting the iron away (c) reading the message (d) cutting the lemon
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) a balloon (d) white paper
38. 38.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
39. 39.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
40. 40.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a balloon (d) white paper

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