Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 443 · 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: a cotton bud is not needed for the secret lemon message. (a) False (b) True
2. 2.True or false: cutting the lemon is a job a child can do. (a) True (b) False
3. 3.True or false: lemon juice is not needed for the secret lemon message. (a) True (b) False
4. 4.🍋 Secret message: who does this step — dipping the cotton bud? (a) an adult does it (b) a child can do it
5. 5.🍋 Why does the lemon writing turn brown with heat? (a) the iron is brown (b) paper turns lemony (c) heat adds colour (d) the juice scorches first
6. 6.True or false: turmeric powder is not needed for the secret lemon message. (a) True (b) False
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) the ink is magnetic (c) the paper ate it (d) dry juice is see-through
8. 8.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) lemon juice (c) yeast (d) an adult with an iron
9. 9.📘 The browning of lemon juice with heat is a ___ change. (a) magnetic (b) musical (c) physical (d) chemical
10. 10.🔮 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
11. 11.🧺 Do we need a battery cell for the secret lemon message? (a) not needed (b) needed
12. 12.True or false: a magnet is not needed for the secret lemon message. (a) True (b) False
13. 13.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “how dark the writing is”? (a) we change it (b) we keep it the same (c) we measure it
14. 14.True or false: a small bowl is not needed for the secret lemon message. (a) True (b) False
15. 15.🔮 Predict: you write with plain water instead of lemon juice. What appears after ironing? (a) a rainbow (b) almost nothing (c) blue words (d) dark brown words
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.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
18. 18.⚖️ 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) the kind of juice (c) the ironing time (d) how dark the writing is
19. 19.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) dipping the cotton bud (c) cutting the lemon (d) plugging in the iron
20. 20.⚖️ 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
21. 21.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) turmeric powder (c) a cotton bud (d) a magnet
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we keep it the same (b) we measure it (c) we change it
23. 23.True or false: an adult with an iron is not needed for the secret lemon message. (a) False (b) True
24. 24.🧺 Do we need yeast for the secret lemon message? (a) not needed (b) needed
25. 25.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) plugging in the iron (d) letting the paper dry
26. 26.True or false: letting the paper dry is a job for an adult. (a) True (b) False
27. 27.⚖️ 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) False (b) True
28. 28.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) wash your hands (c) rub your eyes (d) skip washing
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the ironing time”? (a) we measure it (b) we keep it the same (c) we change it
30. 30.🧺 Do we need a cotton bud for the secret lemon message? (a) needed (b) not needed
31. 31.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
32. 32.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) dipping the cotton bud (d) putting the iron away
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) turmeric powder (c) white paper (d) a mirror
34. 34.🛟 Why must children keep their fingers away from the iron? (a) it is magnetic (b) it can burn skin (c) it is cold (d) it is sticky
35. 35.True or false: a mirror is needed for the secret lemon message. (a) True (b) False
36. 36.🧺 Do we need a mirror for the secret lemon message? (a) needed (b) not needed
37. 37.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a balloon (c) a small bowl (d) lemon juice
38. 38.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
39. 39.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
40. 40.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the ironing time (b) how dark the writing is (c) the kind of juice

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