Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 495 · 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.True or false: white paper is needed for the secret lemon message. (a) False (b) True
2. 2.🍋 Which of these steps is a job a child can do? (a) reading the message (b) cutting the lemon (c) ironing the paper (d) plugging in the iron
3. 3.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) a balloon (c) lemon juice (d) a cotton bud
4. 4.🧺 Do we need a mirror for the secret lemon message? (a) not needed (b) needed
5. 5.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the kind of juice (b) how dark the writing is (c) the ironing time
6. 6.🔮 Can the brown writing go back to being invisible? (a) yes, in the dark (b) yes, if shaken (c) yes, if cooled (d) no, it stays brown
7. 7.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
8. 8.🧺 Which of these is needed for the secret lemon message? (a) a mirror (b) white paper (c) turmeric powder (d) a balloon
9. 9.🔍 Which is the odd one out? (a) reading the message (b) letting the paper dry (c) writing the message (d) cutting the lemon
10. 10.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) skip washing (c) wash your hands (d) lick your fingers
11. 11.🔍 Which is the odd one out? (a) putting the iron away (b) ironing the paper (c) letting the paper dry (d) cutting the lemon
12. 12.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) False (b) True
13. 13.📘 The browning of lemon juice with heat is a ___ change. (a) physical (b) musical (c) magnetic (d) chemical
14. 14.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) an adult with an iron (d) a cotton bud
15. 15.True or false: plugging in the iron is a job for an adult. (a) False (b) True
16. 16.True or false: cutting the lemon is a job a child can do. (a) True (b) False
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) turmeric powder (b) a small bowl (c) an adult with an iron (d) a cotton bud
18. 18.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) plugging in the iron (d) letting the paper dry
19. 19.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
21. 21.🍋 Secret message: who does this step — dipping the cotton bud? (a) a child can do it (b) an adult does it
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) yeast (c) an adult with an iron (d) a cotton bud
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) how dark the writing is (b) the same paper (c) the kind of juice
24. 24.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
25. 25.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) it turned into air (c) the ink is magnetic (d) dry juice is see-through
26. 26.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) True (b) False
27. 27.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
28. 28.🧺 Which of these is needed for the secret lemon message? (a) a cotton bud (b) turmeric powder (c) a mirror (d) a magnet
29. 29.🍋 Secret message: who does this step — ironing the paper? (a) an adult does it (b) a child can do it
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) white paper (c) lemon juice (d) a magnet
31. 31.🧺 Do we need yeast for the secret lemon message? (a) needed (b) not needed
32. 32.⚖️ 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
33. 33.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) putting the iron away (c) ironing the paper (d) dipping the cotton bud
34. 34.True or false: letting the paper dry is a job for an adult. (a) True (b) False
35. 35.🔮 Predict: the adult irons for only one second. What happens? (a) the paper floats (b) it gets darker (c) writing turns green (d) writing stays faint
36. 36.True or false: yeast is needed for the secret lemon message. (a) True (b) False
37. 37.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) writing the message (c) letting the paper dry (d) putting the iron away
38. 38.True or false: ironing the paper is a job for an adult. (a) True (b) False
39. 39.True or false: reading the message is a job for an adult. (a) True (b) False
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we change it (b) we measure it (c) we keep it the same

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