Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 144 · 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? What do we do with “the same paper”? (a) we measure it (b) we keep it the same (c) we change it
2. 2.🍋 Why does the lemon writing turn brown with heat? (a) heat adds colour (b) the juice scorches first (c) the iron is brown (d) paper turns lemony
3. 3.🧺 Do we need a balloon for the secret lemon message? (a) needed (b) not needed
4. 4.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the kind of juice”? (a) we measure it (b) we change it (c) we keep it the same
5. 5.⚖️ 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 ironing time (c) the kind of juice
6. 6.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
7. 7.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) skip washing (b) rub your eyes (c) lick your fingers (d) wash your hands
8. 8.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) any child (d) the youngest child
9. 9.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is magnetic (c) it can burn skin (d) it is cold
10. 10.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
11. 11.True or false: reading the message is a job a child can do. (a) True (b) False
12. 12.🍋 Which of these steps is a job for an adult? (a) letting the paper dry (b) writing the message (c) dipping the cotton bud (d) putting the iron away
13. 13.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) a battery cell (c) lemon juice (d) white paper
14. 14.🔍 Which is the odd one out? (a) putting the iron away (b) cutting the lemon (c) reading the message (d) ironing the paper
15. 15.🧺 Which of these is needed for the secret lemon message? (a) a battery cell (b) a balloon (c) yeast (d) lemon juice
16. 16.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) writing the message (c) putting the iron away (d) cutting the lemon
17. 17.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) white paper (d) a cotton bud
18. 18.🍋 Why can’t you see the lemon writing once it dries? (a) it turned into air (b) dry juice is see-through (c) the paper ate it (d) the ink is magnetic
19. 19.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
20. 20.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
21. 21.🔮 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
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) lemon juice (c) a small bowl (d) yeast
23. 23.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) a cotton bud (d) white paper
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the iron setting (b) how dark the writing is (c) the kind of juice
25. 25.🧺 Which of these is needed for the secret lemon message? (a) turmeric powder (b) yeast (c) white paper (d) a balloon
26. 26.🧺 Which of these is not needed for the secret lemon message? (a) an adult with an iron (b) a cotton bud (c) a balloon (d) white paper
27. 27.True or false: a cotton bud is needed for the secret lemon message. (a) False (b) True
28. 28.⚖️ 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) the same cotton bud (c) the kind of juice (d) the ironing time
29. 29.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is the one thing we change. (a) True (b) False
30. 30.🍋 What colour does the lemon writing turn when an adult warms it? (a) green (b) brown (c) blue (d) white
31. 31.🔍 Which is the odd one out? (a) dipping the cotton bud (b) plugging in the iron (c) writing the message (d) reading the message
32. 32.🍋 Which of these steps is a job a child can do? (a) plugging in the iron (b) ironing the paper (c) cutting the lemon (d) dipping the cotton bud
33. 33.⚖️ 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
34. 34.True or false: ironing the paper is a job a child can do. (a) True (b) False
35. 35.True or false: plugging in the iron is a job for an adult. (a) True (b) False
36. 36.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
37. 37.True or false: white paper is needed for the secret lemon message. (a) False (b) True
38. 38.🔍 Which is the odd one out? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) cutting the lemon
39. 39.🍋 Secret message: who does this step — reading the message? (a) an adult does it (b) a child can do it
40. 40.🔍 Which is the odd one out? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) putting the iron away

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