Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 960 · 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.🧺 Which of these is needed for the secret lemon message? (a) lemon juice (b) a mirror (c) yeast (d) turmeric powder
2. 2.True or false: a balloon is not needed for the secret lemon message. (a) True (b) False
3. 3.True or false: a mirror is not needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) a magnet (c) an adult with an iron (d) turmeric powder
5. 5.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) white paper (b) an adult with an iron (c) a small bowl (d) turmeric powder
6. 6.True or false: putting the iron away is a job for an adult. (a) False (b) True
7. 7.True or false: writing the message is a job a child can do. (a) True (b) False
8. 8.🔍 Which is the odd one out? (a) letting the paper dry (b) plugging in the iron (c) writing the message (d) dipping the cotton bud
9. 9.🔍 Which is the odd one out? (a) cutting the lemon (b) plugging in the iron (c) writing the message (d) putting the iron away
10. 10.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the iron setting is kept the same. (a) True (b) False
11. 11.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is what we measure. (a) True (b) False
12. 12.🍋 Secret message: who does this step — ironing the paper? (a) a child can do it (b) an adult does it
13. 13.True or false: a cotton bud is needed for the secret lemon message. (a) True (b) False
14. 14.⚖️ 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
15. 15.🍋 Secret message: who does this step — plugging in the iron? (a) an adult does it (b) a child can do it
16. 16.True or false: a battery cell is not needed for the secret lemon message. (a) False (b) True
17. 17.🔍 Which is the odd one out? (a) putting the iron away (b) writing the message (c) letting the paper dry (d) dipping the cotton bud
18. 18.🍋 Secret message: who does this step — writing the message? (a) an adult does it (b) a child can do it
19. 19.True or false: dipping the cotton bud is a job for an adult. (a) False (b) True
20. 20.🍋 Secret message: who does this step — letting the paper dry? (a) a child can do it (b) an adult does it
21. 21.🍋 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
22. 22.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the same cotton bud”? (a) we change it (b) we measure it (c) we keep it the same
23. 23.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the ironing time (b) how dark the writing is (c) the kind of juice (d) the same paper
24. 24.True or false: yeast is needed for the secret lemon message. (a) False (b) True
25. 25.🍋 Which of these steps is a job for an adult? (a) plugging in the iron (b) writing the message (c) reading the message (d) dipping the cotton bud
26. 26.🍋 Which of these steps is a job a child can do? (a) putting the iron away (b) ironing the paper (c) cutting the lemon (d) reading the message
27. 27.🔍 Which is the odd one out? (a) putting the iron away (b) plugging in the iron (c) ironing the paper (d) reading the message
28. 28.🍋 Which of these steps is a job a child can do? (a) ironing the paper (b) plugging in the iron (c) letting the paper dry (d) putting the iron away
29. 29.⚖️ 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
30. 30.🧺 Which of these is not needed for the secret lemon message? (a) lemon juice (b) turmeric powder (c) a small bowl (d) a cotton bud
31. 31.🛟 Lemon juice stings cuts and eyes. What should you do after the experiment? (a) lick your fingers (b) skip washing (c) rub your eyes (d) wash your hands
32. 32.⚖️ 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
33. 33.🍋 What colour does the lemon writing turn when an adult warms it? (a) brown (b) white (c) green (d) blue
34. 34.🔮 Can the brown writing go back to being invisible? (a) no, it stays brown (b) yes, if shaken (c) yes, if cooled (d) yes, in the dark
35. 35.🧺 Do we need white paper for the secret lemon message? (a) needed (b) not needed
36. 36.🧺 Which of these is not needed for the secret lemon message? (a) a small bowl (b) white paper (c) lemon juice (d) a mirror
37. 37.🧺 Do we need an adult with an iron for the secret lemon message? (a) needed (b) not needed
38. 38.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the iron is brown (c) heat adds colour (d) the juice scorches first
39. 39.🍋 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) ironing the paper
40. 40.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) the youngest child (c) only an adult (d) any child

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