Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 601 · 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? Which of these is what we measure? (a) the same paper (b) how dark the writing is (c) the same cotton bud (d) the ironing time
2. 2.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) a balloon (c) lemon juice (d) an adult with an iron
3. 3.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
4. 4.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a cotton bud (c) a balloon (d) lemon juice
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we change it (b) we measure it (c) we keep it the same
6. 6.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) writing the message
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) wash your hands (b) rub your eyes (c) skip washing (d) lick your fingers
8. 8.True or false: an adult with an iron is needed for the secret lemon message. (a) True (b) False
9. 9.🍋 Which of these steps is a job for an adult? (a) writing the message (b) plugging in the iron (c) dipping the cotton bud (d) reading the message
10. 10.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it is magnetic (d) it can burn skin
11. 11.True or false: white paper is needed for the secret lemon message. (a) True (b) False
12. 12.⚖️ 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
13. 13.🍋 Secret message: who does this step — writing the message? (a) a child can do it (b) an adult does it
14. 14.🍋 Secret message: who does this step — putting the iron away? (a) a child can do it (b) an adult does it
15. 15.True or false: dipping the cotton bud is a job a child can do. (a) False (b) True
16. 16.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a small bowl (c) an adult with an iron (d) yeast
17. 17.True or false: white paper is not needed for the secret lemon message. (a) False (b) True
18. 18.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) dark brown words (c) a rainbow (d) blue words
19. 19.True or false: putting the iron away is a job for an adult. (a) False (b) True
20. 20.🔮 Predict: the adult irons for only one second. What happens? (a) writing stays faint (b) writing turns green (c) it gets darker (d) the paper floats
21. 21.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) reading the message (c) cutting the lemon (d) letting the paper dry
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) no, it stays brown (c) yes, if shaken (d) yes, if cooled
23. 23.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
24. 24.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
25. 25.True or false: a mirror is needed for the secret lemon message. (a) False (b) True
26. 26.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) physical (c) chemical (d) musical
27. 27.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a magnet (c) white paper (d) an adult with an iron
28. 28.🔍 Which is the odd one out? (a) ironing the paper (b) putting the iron away (c) cutting the lemon (d) dipping the cotton bud
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) True (b) False
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we keep it the same (b) we change it (c) we measure it
31. 31.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
32. 32.True or false: plugging in the iron is a job a child can do. (a) False (b) True
33. 33.True or false: plugging in the iron is a job for an adult. (a) True (b) False
34. 34.🍋 Which of these steps is a job a child can do? (a) reading the message (b) plugging in the iron (c) putting the iron away (d) cutting the lemon
35. 35.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is the one thing we change. (a) False (b) True
36. 36.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is what we measure. (a) True (b) False
37. 37.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
38. 38.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) reading the message (c) writing the message (d) ironing the paper
39. 39.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) a mirror (d) lemon juice
40. 40.🍋 Which of these steps is a job a child can do? (a) writing the message (b) plugging in the iron (c) ironing the paper (d) cutting the lemon

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