Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 811 · 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.🧺 Which of these is not needed for the secret lemon message? (a) turmeric powder (b) a small bowl (c) white paper (d) a cotton bud
2. 2.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) wash your hands (d) lick your fingers
3. 3.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) chemical (d) physical
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is kept the same. (a) False (b) True
5. 5.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) no, it stays brown (c) yes, if cooled (d) yes, in the dark
6. 6.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) an adult with an iron (d) white paper
7. 7.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) False (b) True
8. 8.🧺 Do we need a battery cell for the secret lemon message? (a) needed (b) not needed
9. 9.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) writing turns green (c) it gets darker (d) writing stays faint
10. 10.🧺 Do we need lemon juice for the secret lemon message? (a) not needed (b) needed
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) white paper (c) a mirror (d) a cotton bud
12. 12.🍋 Which of these steps is a job for an adult? (a) putting the iron away (b) letting the paper dry (c) dipping the cotton bud (d) reading the message
13. 13.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
14. 14.🍋 Which of these steps is a job for an adult? (a) reading the message (b) ironing the paper (c) dipping the cotton bud (d) writing the message
15. 15.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
16. 16.🍋 Secret message: who does this step — letting the paper dry? (a) an adult does it (b) a child can do it
17. 17.🍋 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
18. 18.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
19. 19.⚖️ 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
20. 20.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is what we measure. (a) False (b) True
22. 22.🧺 Do we need an adult with an iron for the secret lemon message? (a) not needed (b) needed
23. 23.True or false: writing the message is a job for an adult. (a) False (b) True
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is kept the same. (a) True (b) False
25. 25.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the ironing time is the one thing we change. (a) True (b) False
26. 26.🔍 Which is the odd one out? (a) ironing the paper (b) dipping the cotton bud (c) cutting the lemon (d) putting the iron away
27. 27.True or false: putting the iron away is a job a child can do. (a) True (b) False
28. 28.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) a small bowl (c) an adult with an iron (d) a magnet
29. 29.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) plugging in the iron (d) putting the iron away
30. 30.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the iron setting (b) how dark the writing is (c) the kind of juice (d) the same paper
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: how dark the writing is is kept the same. (a) True (b) False
32. 32.🔍 Which is the odd one out? (a) letting the paper dry (b) dipping the cotton bud (c) writing the message (d) ironing the paper
33. 33.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
34. 34.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
35. 35.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
36. 36.🔍 Which is the odd one out? (a) cutting the lemon (b) writing the message (c) ironing the paper (d) plugging in the iron
37. 37.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
38. 38.True or false: plugging in the iron is a job a child can do. (a) False (b) True
39. 39.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) an adult with an iron (c) yeast (d) a small bowl
40. 40.🛟 Why must children keep their fingers away from the iron? (a) it can burn skin (b) it is cold (c) it is sticky (d) it is magnetic

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