Invisible Ink Experiment Worksheet

Science experiments lesson 13: Lemon juice invisible ink · Set 985 · 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.🛟 Who should use the hot iron in the secret message experiment? (a) whoever is fastest (b) only an adult (c) the youngest child (d) any child
2. 2.⚖️ 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
3. 3.True or false: a cotton bud is not needed for the secret lemon message. (a) False (b) True
4. 4.🧺 Do we need turmeric powder for the secret lemon message? (a) needed (b) not needed
5. 5.True or false: a balloon is not needed for the secret lemon message. (a) False (b) True
6. 6.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a cotton bud (b) lemon juice (c) a small bowl (d) a magnet
7. 7.⚖️ 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
8. 8.🧺 Do we need a cotton bud for the secret lemon message? (a) not needed (b) needed
9. 9.True or false: white paper is needed for the secret lemon message. (a) False (b) True
10. 10.🧺 Do we need a balloon for the secret lemon message? (a) not needed (b) needed
11. 11.True or false: letting the paper dry is a job for an adult. (a) True (b) False
12. 12.🍋 Secret message: who does this step — reading the message? (a) a child can do it (b) an adult does it
13. 13.🍋 Which of these steps is a job for an adult? (a) writing the message (b) ironing the paper (c) reading the message (d) dipping the cotton bud
14. 14.🍋 Which of these steps is a job for an adult? (a) writing the message (b) dipping the cotton bud (c) reading the message (d) putting the iron away
15. 15.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the same cotton bud is kept the same. (a) True (b) False
16. 16.⚖️ 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
17. 17.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is what we measure? (a) the iron setting (b) how dark the writing is (c) the same paper (d) the ironing time
18. 18.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) yeast (b) a cotton bud (c) white paper (d) a small bowl
19. 19.🍋 Which of these steps is a job a child can do? (a) reading the message (b) plugging in the iron (c) ironing the paper (d) cutting the lemon
20. 20.🛟 Why must children keep their fingers away from the iron? (a) it is sticky (b) it is cold (c) it can burn skin (d) it is magnetic
21. 21.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? True or false: the kind of juice is the one thing we change. (a) False (b) True
22. 22.🧺 Do we need white paper for the secret lemon message? (a) not needed (b) needed
23. 23.True or false: a balloon is needed for the secret lemon message. (a) True (b) False
24. 24.🍋 Why does the lemon writing turn brown with heat? (a) paper turns lemony (b) the juice scorches first (c) the iron is brown (d) heat adds colour
25. 25.True or false: a mirror is not needed for the secret lemon message. (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) a balloon (c) a small bowl (d) white paper
27. 27.True or false: putting the iron away is a job for an adult. (a) False (b) True
28. 28.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? What do we do with “the iron setting”? (a) we change it (b) we keep it the same (c) we measure it
29. 29.🍋 Which of these steps is a job a child can do? (a) dipping the cotton bud (b) ironing the paper (c) plugging in the iron (d) putting the iron away
30. 30.🧺 Three of these are needed for the secret lemon message. Which one is NOT needed? (a) a battery cell (b) a small bowl (c) lemon juice (d) white paper
31. 31.🛟 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
32. 32.🍋 Secret message: who does this step — cutting the lemon? (a) a child can do it (b) an adult does it
33. 33.🔮 Can the brown writing go back to being invisible? (a) yes, if shaken (b) yes, in the dark (c) yes, if cooled (d) no, it stays brown
34. 34.🧺 Which of these is not needed for the secret lemon message? (a) white paper (b) lemon juice (c) a small bowl (d) turmeric powder
35. 35.🔍 Which is the odd one out? (a) reading the message (b) putting the iron away (c) dipping the cotton bud (d) writing the message
36. 36.🍋 Secret message: who does this step — putting the iron away? (a) an adult does it (b) a child can do it
37. 37.⚖️ Fair test — does lemon juice or orange juice make darker secret writing? Which of these is the one thing we change? (a) the same cotton bud (b) the same paper (c) how dark the writing is (d) the kind of juice
38. 38.True or false: putting the iron away is a job a child can do. (a) False (b) True
39. 39.🧺 Which of these is needed for the secret lemon message? (a) yeast (b) white paper (c) a battery cell (d) turmeric powder
40. 40.🧺 Which of these is not needed for the secret lemon message? (a) a cotton bud (b) a mirror (c) a small bowl (d) an adult with an iron

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