Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 245 · 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? True or false: the same paper is kept the same. (a) True (b) False
2. 2.🔍 Which is the odd one out? (a) ironing the paper (b) reading the message (c) plugging in the iron (d) cutting the lemon
3. 3.True or false: an adult with an iron is needed for the secret lemon message. (a) False (b) True
4. 4.True or false: ironing the paper is a job a child can do. (a) True (b) False
5. 5.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) putting the iron away (c) ironing the paper (d) plugging in the iron
6. 6.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) any child (c) the youngest child (d) only an adult
7. 7.🍋 Why can’t you see the lemon writing once it dries? (a) the ink is magnetic (b) it turned into air (c) dry juice is see-through (d) the paper ate it
8. 8.🧺 Do we need turmeric powder for the secret lemon message? (a) not needed (b) needed
9. 9.🛟 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
10. 10.🍋 Secret message: who does this step — cutting the lemon? (a) an adult does it (b) a child can do it
11. 11.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a small bowl (b) turmeric powder (c) an adult with an iron (d) a cotton bud
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.🍋 What colour does the lemon writing turn when an adult warms it? (a) white (b) brown (c) green (d) blue
14. 14.🔮 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
15. 15.📘 The browning of lemon juice with heat is a ___ change. (a) chemical (b) musical (c) magnetic (d) physical
16. 16.True or false: writing the message is a job a child can do. (a) False (b) True
17. 17.⚖️ 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 change it (c) we measure it
18. 18.True or false: lemon juice is needed for the secret lemon message. (a) False (b) True
19. 19.⚖️ 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 keep it the same (c) we change it
20. 20.🧺 Do we need lemon juice for the secret lemon message? (a) needed (b) not needed
21. 21.True or false: cutting the lemon is a job a child can do. (a) True (b) False
22. 22.🧺 Which of these is not needed for the secret lemon message? (a) a mirror (b) a small bowl (c) a cotton bud (d) lemon juice
23. 23.True or false: a cotton bud is not needed for the secret lemon message. (a) True (b) False
24. 24.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice 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.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) lemon juice (b) yeast (c) an adult with an iron (d) a small bowl
27. 27.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
28. 28.🔍 Which is the odd one out? (a) dipping the cotton bud (b) writing the message (c) reading the message (d) cutting the lemon
29. 29.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) letting the paper dry (c) putting the iron away (d) cutting the lemon
30. 30.🧺 Which of these is needed for the secret lemon message? (a) a balloon (b) turmeric powder (c) yeast (d) an adult with an iron
31. 31.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is kept the same? (a) the same cotton bud (b) the kind of juice (c) how dark the writing is
32. 32.True or false: a small bowl is not needed for the secret lemon message. (a) False (b) True
33. 33.🧺 Which of these is needed for the secret lemon message? (a) a magnet (b) turmeric powder (c) a balloon (d) white paper
34. 34.True or false: ironing the paper is a job for an adult. (a) False (b) True
35. 35.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) lemon juice (c) an adult with an iron (d) white paper
36. 36.⚖️ 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 change it (c) we keep it the same
37. 37.🍋 Which of these steps is a job a child can do? (a) cutting the lemon (b) ironing the paper (c) reading the message (d) putting the iron away
38. 38.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is what we measure. (a) False (b) True
39. 39.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we measure it (b) we change it (c) we keep it the same
40. 40.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it

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