Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 862 · 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) a cotton bud (c) a small bowl (d) a mirror
2. 2.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
3. 3.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
4. 4.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) ironing the paper (d) dipping the cotton bud
5. 5.True or false: a small bowl is needed for the secret lemon message. (a) False (b) True
6. 6.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) plugging in the iron (c) reading the message (d) putting the iron away
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the paper ate it (b) dry juice is see-through (c) the ink is magnetic (d) it turned into air
8. 8.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the same paper (b) the ironing time (c) the iron setting (d) how dark the writing is
9. 9.True or false: lemon juice is not needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a balloon (b) a cotton bud (c) a small bowl (d) an adult with an iron
11. 11.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) ironing the paper (c) reading the message (d) letting the paper dry
12. 12.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
13. 13.🔮 Predict: the adult irons for only one second. What happens? (a) it gets darker (b) writing turns green (c) writing stays faint (d) the paper floats
14. 14.🛟 Why must children keep their fingers away from the iron? (a) it is cold (b) it is sticky (c) it is magnetic (d) it can burn skin
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same paper (b) how dark the writing is (c) the kind of juice (d) the ironing time
16. 16.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
17. 17.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) rub your eyes (b) lick your fingers (c) wash your hands (d) skip washing
18. 18.True or false: writing the message is a job for an adult. (a) True (b) False
19. 19.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we measure it (b) we keep it the same (c) we change it
20. 20.🍋 What colour does the lemon writing turn when an adult warms it? (a) blue (b) brown (c) green (d) white
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is the one thing we change. (a) False (b) True
22. 22.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) no, it stays brown (d) yes, if cooled
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same paper”? (a) we keep it the same (b) we measure it (c) we change it
24. 24.🍋 Which of these steps is a job for an adult? (a) dipping the cotton bud (b) letting the paper dry (c) plugging in the iron (d) writing the message
25. 25.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
26. 26.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) lemon juice (c) a small bowl (d) a cotton bud
27. 27.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) an adult with an iron (d) yeast
28. 28.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) chemical (c) musical (d) physical
29. 29.⚖️ 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
30. 30.⚖️ 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 measure it (c) we change it
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same paper is the one thing we change. (a) False (b) True
32. 32.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) a small bowl (c) an adult with an iron (d) turmeric powder
33. 33.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
34. 34.⚖️ 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 change it (c) we measure it
35. 35.🧺 Do we need a magnet for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Which of these is needed for the secret lemon message? (a) white paper (b) a mirror (c) a balloon (d) a battery cell
37. 37.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) almost nothing (b) blue words (c) a rainbow (d) dark brown words
38. 38.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
39. 39.True or false: turmeric powder is needed for the secret lemon message. (a) True (b) False
40. 40.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed

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